feat(07-uat): admin AI panel UX enhancements + DocumentCard status indicators

- GET /api/admin/ai-config/models — fetch model list from provider's /models endpoint
- POST /api/admin/ai-config/test-connection — replaced GET; accepts unsaved form
  values (api_key, base_url, model_name) so admins can test before saving
- TestConnectionRequest Pydantic model with provider_id validation
- SearchableModelSelect.vue — new reusable combobox; Teleport to body avoids
  overflow:hidden clipping; shows all models on open, filters only on typing;
  static "Enter manually" item always pinned at bottom; caches per provider
- AdminAiConfigTab: model name input replaced with SearchableModelSelect;
  testingProvider ref + spinner added to Test Connection button
- DocumentCard: processing spinner + "Classifying…", pending "Queued" badge,
  classification_failed badge; topics section only shown when status=ready
- FileManagerView: onUnmounted imported (polling wiring pending next session)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/api/admin.py

@@ -152,6 +152,31 @@ class SystemAiConfigUpdate(BaseModel):
         return v
 
 
+class TestConnectionRequest(BaseModel):
+    """Request body for POST /api/admin/ai-config/test-connection.
+
+    Unsaved form values (api_key, base_url, model_name) override the DB row so
+    admins can verify credentials before saving.  All override fields are optional;
+    omitting them falls back to whatever is stored in system_settings.
+    """
+
+    model_config = ConfigDict(extra="forbid")
+
+    provider_id: str
+    api_key: Optional[str] = None      # If non-empty, used instead of stored api_key_enc
+    base_url: Optional[str] = None     # If non-None, overrides DB base_url
+    model_name: Optional[str] = None   # If non-empty, overrides DB model_name
+
+    @field_validator("provider_id")
+    @classmethod
+    def provider_must_be_known(cls, v: str) -> str:
+        if v not in PROVIDER_DEFAULTS:
+            raise ValueError(
+                f"Unknown provider_id {v!r}. Must be one of: {list(PROVIDER_DEFAULTS.keys())}"
+            )
+        return v
+
+
 class SystemTopicCreate(BaseModel):
     """Request model for admin system topic creation (D-09)."""
 
@@ -628,32 +653,124 @@ async def create_system_topic(
 
 # ── System AI Provider Configuration (D-08, D-15) ────────────────────────────
 
-@router.get("/ai-config/test-connection")
-async def test_ai_connection(
+@router.get("/ai-config/models")
+async def get_ai_config_models(
     provider_id: str,
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> dict:
-    """Test connectivity for an AI provider configuration (D-08).
+    """Return the list of model IDs available from a provider's API (D-08).
 
-    Loads the system_settings row for the given provider_id (ignoring is_active
-    so admins can test inactive configurations), builds a provider instance, and
-    calls health_check().
+    Calls the provider's standard GET /models endpoint using the stored
+    config (base_url + api_key from system_settings).  Always returns 200
+    with {"models": [...]} — never 5xx on provider failure (returns empty list).
 
-    Returns {"ok": true/false, "provider_id": str} — never raises 5xx for
-    provider-side failures (surfaces as ok=False so the UI shows a clear status).
-
-    Security: requires get_current_admin; provider_id sourced from query param,
-    provider instance built only from DB row (never from request body).
+    Security: requires get_current_admin; provider_id from query param only;
+    decrypted api_key never appears in the response.
     """
+    import httpx  # noqa: PLC0415 — local import keeps admin.py startup fast
+
     config = await load_provider_config_by_id(session, provider_id)
-    if config is None:
-        return {"ok": False, "provider_id": provider_id, "reason": "not_configured"}
+
+    # Resolve base_url: prefer DB row, fall back to PROVIDER_DEFAULTS
+    if config and config.base_url:
+        base_url = config.base_url.rstrip("/")
+    else:
+        base_url = (PROVIDER_DEFAULTS.get(provider_id, {}).get("base_url") or "").rstrip("/")
+
+    if not base_url:
+        return {"models": [], "provider_id": provider_id}
+
+    api_key = config.api_key if config else ""
+
+    # Build request headers — Anthropic uses x-api-key; all others use Bearer
+    if provider_id == "anthropic":
+        headers = {
+            "x-api-key": api_key,
+            "anthropic-version": "2023-06-01",
+        }
+        models_url = "https://api.anthropic.com/v1/models"
+    else:
+        headers = {"Authorization": f"Bearer {api_key}"} if api_key else {}
+        models_url = f"{base_url}/models"
 
     try:
-        provider = get_provider(config)
-        await provider.health_check()
-        return {"ok": True, "provider_id": provider_id}
+        async with httpx.AsyncClient(timeout=8.0) as client:
+            resp = await client.get(models_url, headers=headers)
+            resp.raise_for_status()
+            data = resp.json()
+
+        # Standard OpenAI-compat shape: {"data": [{"id": "...", ...}, ...]}
+        # Anthropic shape: {"data": [{"id": "...", ...}, ...]}
+        # Ollama OpenAI-compat: same shape
+        raw_list = data.get("data") or data.get("models") or []
+        model_ids: list[str] = sorted(
+            {
+                item["id"] if isinstance(item, dict) else str(item)
+                for item in raw_list
+                if item
+            }
+        )
+        return {"models": model_ids, "provider_id": provider_id}
+    except Exception as exc:
+        return {"models": [], "provider_id": provider_id, "error": str(exc)[:120]}
+
+
+@router.post("/ai-config/test-connection")
+async def test_ai_connection(
+    body: TestConnectionRequest,
+    session: AsyncSession = Depends(get_db),
+    _admin: User = Depends(get_current_admin),
+) -> dict:
+    """Test connectivity for an AI provider, optionally with unsaved form values (D-08).
+
+    Loads the stored system_settings row for body.provider_id, then overlays any
+    non-empty values from the request body so admins can verify credentials before
+    saving them to the database.
+
+    Override priority (highest → lowest):
+      1. body.api_key / base_url / model_name  (unsaved form values)
+      2. system_settings DB row               (previously saved config)
+      3. PROVIDER_DEFAULTS                    (built-in fallback)
+
+    Returns {"ok": true/false, "provider_id": str} — never raises 5xx for
+    provider-side failures; surfaces as ok=False so the UI shows a clear status.
+
+    Security: requires get_current_admin; api_key from body is used only for the
+    in-flight health_check() call and is never stored or logged.
+    """
+    provider_id = body.provider_id
+    stored = await load_provider_config_by_id(session, provider_id)
+    defaults = PROVIDER_DEFAULTS.get(provider_id, {})
+
+    # Resolve effective values: body overrides DB, DB overrides PROVIDER_DEFAULTS
+    effective_api_key = (
+        body.api_key
+        if body.api_key
+        else (stored.api_key if stored else "")
+    )
+    effective_base_url = (
+        body.base_url
+        if body.base_url is not None
+        else (stored.base_url if stored else defaults.get("base_url"))
+    )
+    effective_model = (
+        body.model_name
+        if body.model_name
+        else (stored.model if stored else defaults.get("model", ""))
+    )
+
+    effective_config = ProviderConfig(
+        provider_id=provider_id,
+        api_key=effective_api_key,
+        base_url=effective_base_url,
+        model=effective_model,
+    )
+
+    try:
+        provider = get_provider(effective_config)
+        ok = await provider.health_check()
+        return {"ok": ok, "provider_id": provider_id}
     except Exception:
         return {"ok": False, "provider_id": provider_id, "reason": "health_check_failed"}