Add pagination, search, and sorting to admin sessions ...

Backend:
- Add count_all and search_list abstract methods to SessionStore
- Implement count_all and search_list in PgSessionStore (SQL with ILIKE)
- Implement count_all and search_list in InMemorySessionStore
- Update /admin/sessions to accept limit, offset, search, sort_by, sort_order
- Return {total, limit, offset, items} from /admin/sessions

Frontend:
- Add search input for sessions in admin panel
- Add clickable sortable column headers with asc/desc toggle
- Add pagination controls (prev/next, page size selector, item count)
- Debounce search input (300ms)

Tests:
- Add integration tests for pagination, offset, search, and sorting
- All 217 tests pass

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Fix legacy session visibility and add WebSocket auth debug logging ...

- pg_session_store: remove OR user_id IS NULL from list_all/list_page
  so legacy sessions are no longer visible to all users
- auth/deps.py: add debug logging at every step of _resolve_user
- websocket.py: add debug logging at every stage of websocket_session

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Multi-user auth via gnexus-auth OAuth + hybrid role/permission model ...

- Integrate gnexus-auth-client-py (GAuthClient) for OAuth flow, token refresh,
  and webhook parsing
- Add navi/auth/ package: User model, Fernet encryptor, client singleton,
  deps (get_current_user, require_admin, require_permission)
- New tables: navi_users, user_auth_sessions (auto-created on startup)
- Session/memory isolation by user_id with legacy NULL support
- Cookie-based auth proxy: /auth/login, /callback, /logout, /me
- Webhook receiver /webhooks/gnexus-auth handling user events, global logout,
  session revocation, role/permission changes
- Admin endpoints (/admin/*) gated by role + permissions
- Webclient auth store with isAdmin/hasPermission guards
- Admin-only profile filtering in /agents/profiles
- 200/200 tests passing

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Paginate session list loading

Planning debug panel, todo auto-populate, scratchpad/persona improvements ...

- Planning debug panel: new Planning tab in debug/index.html shows raw
  phase 1/2 outputs and token counts per planning run, stored in
  session.planning_logs (new column in both SQLite and PostgreSQL)
- New GET /sessions/{id}/planning API endpoint
- PlanningDebugData internal event wires _run_planning() output into
  session storage; never forwarded to WebSocket clients
- Phase 3 (plan critic) disabled — to be reworked with reflect integration
- Todo tool: auto-populated from plan steps after phase 2; model only
  needs to call update/view, not set
- Scratchpad: clarified description and persona instructions; removed
  context_transfer from user-facing docs (internal mechanism only)
- web_search: switched to ddgs package, SearXNG as primary backend,
  DDG html-only fallback; added find_up action to filesystem tool
- Persona: added SCRATCHPAD and TODO sections with clear usage rules;
  added NAVI.md project context instructions
- chat.js: fixed subagent planning event fallthrough into parent UI;
  statusLabel cleared on first stream delta

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

Add session name generation via LLM ...

Backend:
- Session model gets name: str | None field
- SQLite migration: ADD COLUMN name TEXT
- PostgreSQL: ADD COLUMN IF NOT EXISTS name TEXT (applied on pool init)
- SessionStore: add set_name() abstract method, implemented in all stores
- navi/core/name_generator.py: LLM worker that reads user messages and
  returns a 3–6 word title or None if content isn't substantial yet
- POST /sessions/{id}/generate-name endpoint: fires LLM, saves and
  returns name; skips if session already named or has no user messages
- GET /sessions and GET /sessions/{id} now include name field

Client:
- api.generateSessionName(id) — calls the new endpoint
- sessions store: updateName(id, name) mutation
- chat store: after stream_end, _tryGenerateName() runs fire-and-forget;
  skips silently if session already has a name or if request fails
- SessionItem already displays session.name (falls back to id prefix)

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

Migrate storage to PostgreSQL with SQLite fallback; misc fixes ...

- Add PgSessionStore (asyncpg pool) and PgMemoryStore replacing aiosqlite
- Keep SqliteSessionStore + SqliteMemoryStore for zero-dependency quick start
- Selection logic in deps.py: DATABASE_URL set → PG, else → SQLite
- Add asyncpg>=0.29 to dependencies; add DATABASE_URL / DB_PATH to config
- Add RESPONSE HYGIENE rule to persona: never echo tool output or plan state
- Add developer profile user tools: weather, internal_monitor
- Update README: developer profile, DB section, current tool/profile state

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