feat(example-images): add NSFW level setting endpoint

Add new POST endpoint `/api/lm/example-images/set-nsfw-level` to allow updating NSFW classification for individual example images. The endpoint supports both regular and custom images, validates required parameters, and updates the corresponding model metadata. This enables users to manually adjust NSFW ratings for better content filtering.

static/js/components/shared/NsfwLevelSelector.js

@@ -0,0 +1,126 @@
+import { getNSFWLevelName } from '../../utils/uiHelpers.js';
+import { translate } from '../../utils/i18nHelpers.js';
+
+let selectorController = null;
+
+function buildController(selectorElement) {
+    if (!selectorElement) return null;
+
+    const levelButtons = Array.from(selectorElement.querySelectorAll('.nsfw-level-btn'));
+    const closeBtn = selectorElement.querySelector('.close-nsfw-selector');
+    const currentLevelEl = selectorElement.querySelector('#currentNSFWLevel');
+
+    let onSelect = null;
+    let onClose = null;
+    let isOpen = false;
+    let ignoreNextOutside = false;
+
+    const setLabel = (level, multipleLabel) => {
+        if (!currentLevelEl) return;
+        if (multipleLabel) {
+            currentLevelEl.textContent = multipleLabel;
+            return;
+        }
+        currentLevelEl.textContent = getNSFWLevelName(level);
+    };
+
+    const hide = () => {
+        selectorElement.style.display = 'none';
+        isOpen = false;
+        if (typeof onClose === 'function') {
+            onClose();
+        }
+        onSelect = null;
+        onClose = null;
+    };
+
+    const show = ({ currentLevel = 0, onSelect: selectCb, onClose: closeCb, multipleLabel = '' } = {}) => {
+        onSelect = selectCb || null;
+        onClose = closeCb || null;
+        isOpen = true;
+        ignoreNextOutside = true; // ignore the click that triggered open
+
+        // Position near center of viewport
+        const viewportWidth = document.documentElement.clientWidth;
+        const viewportHeight = document.documentElement.clientHeight;
+        const rect = selectorElement.getBoundingClientRect();
+        const finalX = Math.max((viewportWidth - rect.width) / 2, 0);
+        const finalY = Math.max((viewportHeight - rect.height) / 2, 0);
+
+        selectorElement.style.left = `${finalX}px`;
+        selectorElement.style.top = `${finalY}px`;
+
+        setLabel(currentLevel, multipleLabel);
+
+        // Highlight selected level (if not showing multiple values)
+        levelButtons.forEach((btn) => {
+            const btnLevel = parseInt(btn.dataset.level || '0', 10);
+            if (multipleLabel) {
+                btn.classList.remove('active');
+            } else if (btnLevel === currentLevel) {
+                btn.classList.add('active');
+            } else {
+                btn.classList.remove('active');
+            }
+        });
+
+        selectorElement.style.display = 'block';
+    };
+
+    if (closeBtn) {
+        closeBtn.addEventListener('click', hide);
+    }
+
+    document.addEventListener('click', (e) => {
+        if (!isOpen) return;
+        if (ignoreNextOutside) {
+            ignoreNextOutside = false;
+            return;
+        }
+        if (!selectorElement.contains(e.target)) {
+            hide();
+        }
+    });
+
+    levelButtons.forEach((btn) => {
+        btn.addEventListener('click', async () => {
+            if (!isOpen) return;
+            const level = parseInt(btn.dataset.level || '0', 10);
+            if (typeof onSelect === 'function') {
+                try {
+                    const result = await onSelect(level);
+                    if (result === false) {
+                        return;
+                    }
+                } catch (error) {
+                    console.error('NSFW selector onSelect failed', error);
+                    return;
+                }
+            }
+            hide();
+        });
+    });
+
+    const showMultiple = (labelKey = 'modals.contentRating.multiple') => {
+        const fallback = 'Multiple values';
+        const text = translate(labelKey, {}, fallback);
+        show({ multipleLabel: text });
+    };
+
+    return {
+        show,
+        hide,
+        showMultiple,
+        isOpen: () => isOpen,
+    };
+}
+
+export function getNsfwLevelSelector() {
+    if (selectorController) {
+        return selectorController;
+    }
+
+    const element = document.getElementById('nsfwLevelSelector');
+    selectorController = buildController(element);
+    return selectorController;
+}