feat(recipes): delegate CivitAI-image re-import to companion browser extension

Recipes imported from CivitAI image URLs can contain 0 LoRAs: the backend
only sees the REST image API + EXIF, while the complete generation data
lives in the image page's internal trpc payload (see
docs/recipe-civitai-image-no-metadata.md). When the companion
lm-civitai-extension is installed with a valid license, re-import (single
and bulk) of CivitAI-image-sourced recipes is now delegated to the
extension via DOM CustomEvents; the extension scrapes the image page with
the user's session and calls back into the reimport endpoint with the
full metadata payload. Without the extension (or with an invalid license)
the native path runs unchanged.

- POST /api/lm/recipe/{id}/reimport accepts optional payload params
  (image_url/name/resources/gen_params/base_model/tags); the payload path
  reuses the import-remote engine with reimport semantics (user-edit
  carryover, delete-after-save), and malformed/failed payloads fall back
  to the legacy URL import. Response gains loras_count.
- The endpoint also accepts GET: the extension is GET-only by convention
  (documented in AGENTS.md).
- New static/js/utils/extensionReimportBridge.js (probeExtension /
  delegateReimport / getCivitaiImageInfo) wired into RecipeContextMenu
  and BulkManager with silent native fallback.
- i18n: toast.recipes.reimportingViaExtension added and translated in
  all 9 locales.

static/js/utils/extensionReimportBridge.js

@@ -0,0 +1,220 @@
+/**
+ * Bridge to the companion LoRA Manager browser extension.
+ *
+ * The extension can re-import recipes sourced from CivitAI image pages with
+ * the complete page metadata (internal trpc data scraped with the user's
+ * session), fixing recipes that the native import (REST API + EXIF only)
+ * saved with 0 LoRAs.
+ *
+ * Protocol: DOM CustomEvents on `document`; `detail` is ALWAYS a JSON
+ * string on both sides.
+ *
+ *   LM page -> extension: `lm:reimportProbe`, detail `{}`.
+ *   extension -> LM page: `lm:reimportProbeResult`,
+ *     detail `{supported, licenseValid, extensionVersion?, reason?}`.
+ *   LM page -> extension: `lm:reimportViaExtension`,
+ *     detail `{requestId, recipes: [{recipeId, imageId, imageUrl, title}]}`.
+ *   extension -> LM page: `lm:reimportProgress`,
+ *     detail `{requestId, current, total, recipeId, title, status, message?}`.
+ *   extension -> LM page: `lm:reimportBatchDone`,
+ *     detail `{requestId, completed, failed}`.
+ */
+
+const PROBE_EVENT = 'lm:reimportProbe';
+const PROBE_RESULT_EVENT = 'lm:reimportProbeResult';
+const REIMPORT_EVENT = 'lm:reimportViaExtension';
+const PROGRESS_EVENT = 'lm:reimportProgress';
+const BATCH_DONE_EVENT = 'lm:reimportBatchDone';
+
+const DEFAULT_PROBE_TIMEOUT_MS = 500;
+// Generous batch timeout; any progress event resets it (heartbeat).
+const DEFAULT_REIMPORT_TIMEOUT_MS = 3 * 60 * 1000;
+
+// Mirrors py/utils/civitai_utils.py (_SUPPORTED_CIVITAI_PAGE_HOSTS).
+const SUPPORTED_CIVITAI_PAGE_HOSTS = new Set([
+    'civitai.com',
+    'civitai.red',
+    'civitai.green',
+]);
+
+/**
+ * Parse the JSON-string `detail` of a protocol event.
+ * @param {CustomEvent} event
+ * @returns {object|null} Parsed detail object, or null when absent/invalid.
+ */
+function parseDetail(event) {
+    try {
+        const detail = JSON.parse(event?.detail ?? 'null');
+        return detail && typeof detail === 'object' ? detail : null;
+    } catch {
+        return null;
+    }
+}
+
+/**
+ * Dispatch a protocol event with a JSON-stringified detail.
+ * @param {string} type - Event name.
+ * @param {object} payload - Detail payload (JSON-stringified).
+ */
+function dispatchProtocolEvent(type, payload) {
+    document.dispatchEvent(
+        new CustomEvent(type, { detail: JSON.stringify(payload ?? {}) })
+    );
+}
+
+/**
+ * Generate a correlation id for a re-import batch.
+ * @returns {string}
+ */
+function generateRequestId() {
+    if (globalThis.crypto?.randomUUID) {
+        return globalThis.crypto.randomUUID();
+    }
+    return `lm-${Date.now()}-${Math.random().toString(36).slice(2, 10)}`;
+}
+
+/**
+ * Probe whether the companion extension is installed and usable.
+ *
+ * @param {{timeoutMs?: number}} [options]
+ * @returns {Promise<{supported: boolean, licenseValid: boolean, extensionVersion?: string, reason?: string}|null>}
+ *   Resolves with the probe result, or null when the extension is absent or
+ *   too old to answer (timeout).
+ */
+export function probeExtension({ timeoutMs = DEFAULT_PROBE_TIMEOUT_MS } = {}) {
+    return new Promise((resolve) => {
+        let settled = false;
+        const timer = setTimeout(() => finish(null), timeoutMs);
+
+        const finish = (value) => {
+            if (settled) return;
+            settled = true;
+            clearTimeout(timer);
+            document.removeEventListener(PROBE_RESULT_EVENT, onResult);
+            resolve(value);
+        };
+
+        const onResult = (event) => {
+            const detail = parseDetail(event);
+            if (!detail) return;
+            finish({
+                supported: Boolean(detail.supported),
+                licenseValid: Boolean(detail.licenseValid),
+                extensionVersion: detail.extensionVersion,
+                reason: detail.reason,
+            });
+        };
+
+        document.addEventListener(PROBE_RESULT_EVENT, onResult);
+        dispatchProtocolEvent(PROBE_EVENT, {});
+    });
+}
+
+/**
+ * Delegate a batch of recipe re-imports to the companion extension.
+ *
+ * @param {Array<{recipeId: string, imageId: number, imageUrl: string, title: string}>} recipes
+ * @param {{onProgress?: (progress: object) => void, timeoutMs?: number}} [options]
+ * @returns {Promise<{completed: number, failed: number}>} Resolves on
+ *   `lm:reimportBatchDone`; rejects on timeout. Listeners are cleaned up in
+ *   all outcomes.
+ */
+export function delegateReimport(recipes, { onProgress, timeoutMs = DEFAULT_REIMPORT_TIMEOUT_MS } = {}) {
+    return new Promise((resolve, reject) => {
+        if (!Array.isArray(recipes) || recipes.length === 0) {
+            reject(new Error('delegateReimport requires a non-empty recipe list'));
+            return;
+        }
+
+        const requestId = generateRequestId();
+        let settled = false;
+        let timer = null;
+
+        const cleanup = () => {
+            clearTimeout(timer);
+            document.removeEventListener(PROGRESS_EVENT, onProgressEvent);
+            document.removeEventListener(BATCH_DONE_EVENT, onBatchDone);
+        };
+        const succeed = (value) => {
+            if (settled) return;
+            settled = true;
+            cleanup();
+            resolve(value);
+        };
+        const fail = (error) => {
+            if (settled) return;
+            settled = true;
+            cleanup();
+            reject(error);
+        };
+        const armTimer = () => {
+            clearTimeout(timer);
+            timer = setTimeout(
+                () => fail(new Error('Extension re-import timed out')),
+                timeoutMs
+            );
+        };
+
+        const onProgressEvent = (event) => {
+            const detail = parseDetail(event);
+            if (!detail || detail.requestId !== requestId) return;
+            // Heartbeat: any progress for this batch resets the timeout.
+            armTimer();
+            if (typeof onProgress === 'function') {
+                try {
+                    onProgress(detail);
+                } catch (error) {
+                    console.error('[extensionReimportBridge] onProgress callback failed:', error);
+                }
+            }
+        };
+        const onBatchDone = (event) => {
+            const detail = parseDetail(event);
+            if (!detail || detail.requestId !== requestId) return;
+            succeed({
+                completed: Number.isInteger(detail.completed) ? detail.completed : 0,
+                failed: Number.isInteger(detail.failed) ? detail.failed : 0,
+            });
+        };
+
+        document.addEventListener(PROGRESS_EVENT, onProgressEvent);
+        document.addEventListener(BATCH_DONE_EVENT, onBatchDone);
+        armTimer();
+        dispatchProtocolEvent(REIMPORT_EVENT, { requestId, recipes });
+    });
+}
+
+/**
+ * Extract CivitAI image page info from a recipe source_path.
+ * Mirrors py/utils/civitai_utils.py `extract_civitai_image_id`.
+ *
+ * @param {string|null} sourcePath - Recipe source_path.
+ * @returns {{imageId: number, imageUrl: string}|null} Null when the path is
+ *   not a `/images/<id>` URL on civitai.com/.red/.green.
+ */
+export function getCivitaiImageInfo(sourcePath) {
+    if (!sourcePath || typeof sourcePath !== 'string') {
+        return null;
+    }
+
+    let parsed;
+    try {
+        parsed = new URL(sourcePath);
+    } catch {
+        return null;
+    }
+
+    if (parsed.protocol !== 'http:' && parsed.protocol !== 'https:') {
+        return null;
+    }
+    if (!SUPPORTED_CIVITAI_PAGE_HOSTS.has(parsed.hostname.toLowerCase())) {
+        return null;
+    }
+
+    const pathMatch = parsed.pathname.match(/\/images\/(\d+)/);
+    if (!pathMatch) {
+        return null;
+    }
+
+    return { imageId: Number(pathMatch[1]), imageUrl: sourcePath };
+}