Split monolithic CLAUDE.md into per-service sub-files

Root CLAUDE.md now contains only project-wide concerns (stack, architecture,
Docker, workflows, security hook). Service-specific details moved to:
- backend/CLAUDE.md — DB models, API endpoints, JWT/bcrypt, naming conventions
- frontend/CLAUDE.md — routes, TanStack Query patterns, XSS prevention
- features/ai-service/CLAUDE.md — queue endpoints, provider notes
- features/doc-service/CLAUDE.md — document models, PDF limits, proxy endpoints

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

features/ai-service/CLAUDE.md

@@ -0,0 +1,50 @@
+# ai-service — Claude context
+
+AI provider intermediary, port 8010 (internal only — never proxied to the browser). Accepts chat requests from `doc-service` (and potentially other callers). Manages a priority queue and abstracts over multiple AI providers (Anthropic, Ollama/LM Studio). See root `CLAUDE.md` for architecture, Docker, and project-wide workflows.
+
+---
+
+## File & Folder Tree
+
+```
+features/ai-service/
+├── app/
+│   ├── main.py                    ← FastAPI, queue worker lifespan
+│   ├── core/
+│   │   └── config.py              ← Settings via pydantic-settings
+│   ├── providers/
+│   │   ├── base.py                ← AIProvider abstract class
+│   │   ├── anthropic_provider.py  ← Anthropic API integration
+│   │   └── openai_compat.py       ← Ollama / LM Studio compatibility
+│   ├── routers/
+│   │   ├── chat.py                ← POST /chat (sync, NORMAL priority queue)
+│   │   ├── health.py              ← GET /health
+│   │   ├── queue.py               ← GET /queue/status, /pause, /resume, /cancel/{id}
+│   │   └── plugin.py              ← GET /plugin/manifest (access rules for ai-service-admin group)
+│   └── services/
+│       └── queue.py               ← Priority queue (CRITICAL > HIGH > NORMAL)
+├── Dockerfile                     ← python:3.12-slim, non-root user 1001
+└── STATUS.md
+```
+
+---
+
+## API Endpoints (internal only)
+
+| Method | Path | Description |
+|--------|------|-------------|
+| POST | `/chat` | Chat request (queued at NORMAL priority) |
+| GET | `/health` | Health check |
+| GET | `/queue/status` | Queue state |
+| POST | `/queue/pause` | Pause queue |
+| POST | `/queue/resume` | Resume queue |
+| POST | `/queue/cancel/{job_id}` | Cancel job |
+| GET | `/plugin/manifest` | Plugin manifest (access rules for ai-service-admin group) |
+
+These endpoints are only reachable on `backend-net`. The backend does not expose them to the browser.
+
+---
+
+## Note on timeout and retry configuration
+
+Caller-side timeout and retry settings live in `features/doc-service/app/services/ai_client.py` — see `features/doc-service/CLAUDE.md` for the values.