docs: add CI/CD gotchas and Linux venv path to CLAUDE.md

Added lessons learned: AI tests need ai_enabled mock in CI (#28),
ESLint no-unused-vars lacks argsIgnorePattern (#29). Added Linux venv
activation path and gh CLI commands for CI debugging.

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

CLAUDE.md

@@ -148,7 +148,8 @@ VITE_API_URL=http://localhost:8000
 docker start patherly_postgres
 
 # Backend (from backend/)
-.\venv\Scripts\Activate
+source venv/bin/activate        # Linux/Mac
+# .\venv\Scripts\Activate       # Windows
 uvicorn app.main:app --reload
 
 # Frontend (from frontend/)
@@ -172,6 +173,12 @@ docker exec -it patherly_postgres psql -U postgres -d patherly
 
 # Seed data
 cd backend && pip install httpx && python -m scripts.seed_trees
+
+# CI/CD debugging
+gh run list --limit 5                          # Recent CI runs
+gh run view <id> --log-failed                  # Failed job logs
+gh run watch <id> --exit-status                # Watch run until complete
+gh run view <id> --json jobs --jq '.jobs[] | {name: .name, conclusion: .conclusion}'
 ```
 
 ### URLs
@@ -279,6 +286,10 @@ navigate(`/trees/${newTree.id}/edit`)
 
 **27. Maintenance batch sessions are created all-at-once at launch:** All sessions in a batch exist immediately after `batchLaunchApi.launch()` with `batch_id` + `target_label` set. `started_at` is null until a user begins executing that target — there is no "pending session creation" state.
 
+**28. AI tests in CI need `ai_enabled` mock:** Backend tests that hit AI endpoints must mock `settings.ai_enabled = True` via `PropertyMock` since CI has no `ANTHROPIC_API_KEY`. See `tests/test_ai_chat.py` `_enable_ai` fixture pattern.
+
+**29. ESLint `no-unused-vars` has no `argsIgnorePattern`:** Underscore-prefixed callback params (e.g., `_count`) still trigger errors. Use `// eslint-disable-next-line @typescript-eslint/no-unused-vars` or remove the param if the type signature allows it.
+
 ---
 
 ## RBAC & Permissions