T10: Monitoring, Performance, Documentation & Environment Config — 38 tests, ruff clean, docs OK

- Extended health endpoint: DB+Redis+Storage+Worker checks with degraded status
- Prometheus metrics endpoint: admin-only, text/plain format
- Metrics: http_requests_total, db_pool_connections, arq_jobs_total
- Structured JSON logging (structlog): timestamp, level, method, path, status, duration_ms, tenant_id
- Performance: page_size max 100 enforced (422), streaming CSV export (StreamingResponse)
- Scripts: seed_perf_data.py, check_indexes.py
- Docs: admin-guide.md (Deploy, Backup, Restore, Env-Vars, Troubleshooting), api-overview.md
- README updated: prod setup, API section, env profiles, admin-guide link
- .env.example: added SECRET_KEY, STORAGE_PATH, SMTP_* vars
- 38 new tests, full regression 564/564 pass (0 failures)
- Ruff: all checks passed

.a0/project_state.json

@@ -1,10 +1,10 @@
 {
   "project_name": "leocrm",
   "phase": "phase-3-implementation",
-  "status": "T08a_complete_2_tasks_remaining",
-  "last_commit": "0962f3a",
-  "completed_tasks": ["T01","T02","T03","T04","T05","T06","T07a","T07b","T08a","T08b","T09","T11"],
+  "status": "T08c_complete_1_task_remaining",
+  "last_commit": "0070fb3",
+  "completed_tasks": ["T01","T02","T03","T04","T05","T06","T07a","T07b","T08a","T08b","T08c","T09","T11"],
   "current_task": null,
-  "next_task": "T08c",
-  "updated_at": "2026-07-01T16:54:00+02:00"
+  "next_task": "T10",
+  "updated_at": "2026-07-01T20:44:00+02:00"
 }