Add doc-service tests, AI category suggestions, LM Studio default

- pytest suite for doc-service: 20+ tests covering category CRUD,
  document upload/get/delete/patch, ownership isolation, category
  assignment, AI processing (mock), and live PDF tests (auto-skipped
  when tests/pdfs/ is empty)
- Minimal in-memory PDF builder in conftest so tests run without any
  fixture files; real PDFs can be dropped into tests/pdfs/ to activate
  live extraction tests
- AI prompt updated to return suggested_categories (2–5 short names)
- Frontend: SuggestionChip component in DocumentRow shows AI-suggested
  categories after processing; "Assign" links to an existing category,
  "Create & Assign" creates it first, ✕ dismisses locally
- Default AI provider changed to LM Studio at
  http://host.docker.internal:1234/v1 (host.docker.internal resolves
  to the macOS host from inside Docker Desktop)
- tests/pdfs/ directory tracked via .gitkeep; *.pdf excluded by .gitignore

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

features/doc-service/app/services/config_reader.py

@@ -12,10 +12,13 @@ from app.core.config import settings
 
 _DEFAULT_CONFIG: dict = {
     "ai": {
-        "provider": "anthropic",
+        # Default: LM Studio running on the host machine at port 1234.
+        # Inside Docker, host.docker.internal resolves to the host; for local
+        # dev outside Docker use http://localhost:1234/v1 instead.
+        "provider": "lmstudio",
         "anthropic": {"api_key": "", "model": "claude-haiku-4-5-20251001"},
-        "ollama": {"base_url": "http://localhost:11434/v1", "model": "llama3.2", "api_key": "ollama"},
-        "lmstudio": {"base_url": "http://localhost:1234/v1", "model": "local-model", "api_key": ""},
+        "ollama": {"base_url": "http://host.docker.internal:11434/v1", "model": "llama3.2", "api_key": "ollama"},
+        "lmstudio": {"base_url": "http://host.docker.internal:1234/v1", "model": "local-model", "api_key": "lm-studio"},
     },
     "documents": {"max_pdf_bytes": 20 * 1024 * 1024},
 }