refactor(agent): apply model-source data without an LLM

`_build_prompt_context()` was only reached when the LLM was configured,
so a user with no provider got nothing at all from a linked model source
— no preview, no example images, no author summary, no tags — even
though all of that is deterministic data from a public API.

Split the model-card fetch into `_load_source_card()`, which runs for
every source-backed enrichment, and have the post-processor apply its
result whether or not the LLM runs. The prompt is then built from the
already-fetched card rather than re-fetching it.

Invoking "Enrich Metadata with AI" still always calls the provider; a
model source supplying a description, images and tags is not treated as
a reason to skip it, since the LLM's summary and notes are richer and an
action that silently does not call out to the provider would be
unpredictable. The site data acts as a fallback for the gaps the LLM
leaves.

Add `base_model_resolver.resolve_base_model()` to map the site's own
names (`krea/Krea-2-Turbo`, `KREA_2_TURBO`) onto the canonical
vocabulary, used only when the LLM returns no base model. It is strictly
conservative — exact normalised matching plus a bounded set of variant
suffixes, and it only ever returns a name that is already in the
vocabulary — so an uncertain hint defers to the LLM instead of writing a
plausible-looking wrong value.

docs/agent_skills.md

@@ -78,19 +78,62 @@ TensorArt is link-only: `tensor.art` sits behind a Cloudflare managed challenge
 
 **What it does**:
 1. Reads the model's `.metadata.json` to get the source (`source_platform` + `source_url`, or the legacy `hf_url`)
-2. Fetches the model card through the provider in `py/services/model_sources/`
-3. Sends the README + local metadata to the LLM for structured extraction
+2. Fetches the model card through the provider in `py/services/model_sources/` — the README via `fetch_model_card()`, plus any extras the site keeps outside it via `fetch_model_card_context()`
+3. Sends the README + site-provided extras + local metadata to the LLM for structured extraction
 4. Writes extracted fields to `.metadata.json`:
    - `base_model` — only if current value is empty
    - `trainedWords` — trigger words (LoRA only, if none exist)
-   - `modelDescription` — concise summary (if none exists)
+   - `modelDescription` — the site's author description (if any) followed by the README rendered as HTML
    - `tags` — merged with existing tags, deduplicated
+   - `civitai.images` — example images
    - `metadata_source` — audit trail: `agent:enrich_hf_metadata`
    - `llm_enriched_at` — ISO timestamp
-5. Downloads and optimizes preview image (if LLM found one in the README)
+5. Downloads and optimizes a preview image, using the per-file example image the
+   site publishes when the README has none
 6. Updates the scanner cache
 7. Broadcasts WebSocket progress events
 
+#### Site-provided card extras (`fetch_model_card_context`)
+
+A model card is not always just `README.md`. ModelScope keeps the author's
+summary (`Description`), the site-curated tags (`OfficialTags`), and — per
+published version — the model filenames together with that file's example
+images (`MuseInfo.versions[].coverImages`) and trigger words in its
+model-detail API. AIGC repositories there often ship an auto-generated
+boilerplate README and put everything useful in `Description`, so reading only
+the README yields almost nothing.
+
+Providers opt in by overriding `ModelSource.fetch_model_card_context()`, which
+returns a `ModelCardContext`. Example images are matched to the model's
+**basename**, so each checkpoint in a collection repo gets its own images.
+Sites with no such extras inherit an empty context, and the pipeline behaves
+exactly as before.
+
+#### Deterministic data is applied whether or not an LLM is configured
+
+`AgentService._load_source_card()` runs for every source-backed enrichment, and
+the post-processor applies what it returns before the LLM output is merged. A
+user with **no** provider configured therefore still gets the author summary,
+the example images, the preview, the site-curated tags, the trigger words and
+the README rendered as the model description.
+
+The LLM is always consulted when one is configured — invoking **Enrich Metadata
+with AI** must call the provider every time, and the site data is never treated
+as a reason to skip it. The deterministic values act as fallbacks that fill
+gaps the LLM leaves behind:
+
+| Field | Deterministic source | LLM role |
+| --- | --- | --- |
+| `modelDescription` | author summary + README as HTML | — |
+| `civitai.images` | site example images, then README images | — |
+| `preview_url` | first available example image | may propose one from the README |
+| `tags` | site-curated tags, always merged in | proposes additional content tags |
+| `civitai.description` | author summary | richer 1-2 sentence summary wins |
+| `base_model` | site hints resolved against the canonical vocabulary (`py/services/agent/base_model_resolver.py`) | mapping it is the LLM's job; the resolver only fills in when the LLM returns nothing |
+| `trainedWords` | per-file site trigger words, then YAML `instance_prompt` | primary extraction |
+| `usage_tips` | regex over an explicitly stated strength range | primary extraction |
+| `notes` | — | LLM-only |
+
 Models with no source, an unknown source, or a source without model-card access (TensorArt) are skipped with an explicit reason and counted in the run summary.
 
 **Model types**: LoRA, Checkpoint, Embedding