refactor: rename MERGE_CHECKLIST to ALL_TESTS + add per-service test files

- tests/MERGE_CHECKLIST.md → tests/ALL_TESTS.md (git rename, updated header + index of sub-files)
- tests/backend_tests.md — §1–9, §18 (auth, users, admin, groups, appearance, service health, plugins, AI/doc settings, infra/security)
- tests/frontend_tests.md — §19 (UI & routing)
- tests/doc-service_tests.md — §10–16 (upload/processing, list/filtering, slide-over, sharing, categories, bulk actions, watch directory)
- tests/ai-service_tests.md — §17 (AI queue & providers)
- CLAUDE.md: updated merge checklist section, file tree, and self-update checkpoint with mandatory test-file update rule
- settings.local.json: added docker inspect/ps, curl, lsof, git merge/branch/log/diff/status/config/mv permissions

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

tests/ai-service_tests.md

@@ -0,0 +1,36 @@
+# AI-Service Tests
+
+Tests covering the AI provider intermediary (`ai-service:8010`): health, provider configuration, synchronous chat, the priority queue (enqueue/poll/cancel/pause/resume), and provider timeout.
+
+Full combined suite: `tests/ALL_TESTS.md`
+
+**Test environment:** Feature stack at `http://localhost:$PORT` (see CLAUDE.md §Feature branch workflow).
+**Admin credentials:** any superuser account created during stack setup.
+
+---
+
+## Legend
+
+| Symbol | Meaning |
+|--------|---------|
+| ✅ | Pass |
+| ❌ | Fail |
+| — | N/A for this change |
+
+---
+
+## 17. AI Service — Queue & Providers
+
+| # | Test | Steps | Expected |
+|---|------|-------|----------|
+| 17.1 | Health check | `GET /health` on ai-service (via backend services endpoint) | `{"status": "ok"}` |
+| 17.2 | Provider health | `GET /health/provider` | Active provider name, model, configured=true |
+| 17.3 | Unconfigured provider | Set provider to "anthropic" with empty API key → test connection | 503 or 502 with clear error |
+| 17.4 | Sync chat | `POST /chat` with valid messages array | Response returned synchronously |
+| 17.5 | Queue — async job | `POST /queue/jobs` | `job_id` returned immediately |
+| 17.6 | Queue — poll job | `GET /queue/jobs/{id}` after enqueue | Returns status (`pending` → `done`) and result |
+| 17.7 | Queue — cancel job | `DELETE /queue/jobs/{id}` before processing | Job removed; status = cancelled |
+| 17.8 | Queue pause | `POST /queue/pause` | 204; current job finishes; no new jobs picked up |
+| 17.9 | Queue resume | `POST /queue/resume` after pause | 204; worker resumes; pending jobs process |
+| 17.10 | Priority ordering | Enqueue LOW then HIGH job | HIGH job processed first |
+| 17.11 | Provider timeout | `POST /chat` when provider is unreachable | 504 returned after timeout |