Update docs for admin pagination, search, sorting and memory all_users ...

- docs/api.md:
  - GET /admin/sessions: document pagination (limit/offset), search,
    sort_by and sort_order query params; switch response to {total,
    limit, offset, items} envelope.
  - GET /admin/memory: same pagination/sort docs, {total, limit,
    offset, items} envelope.

- docs/memory.md:
  - get_all_facts signature now includes offset, search, sort_by,
    sort_order and all_users parameters.

- docs/sessions.md:
  - Document count_all and search_list store methods.

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

Document multi-user auth system ...

- New docs/auth.md — comprehensive auth guide: OAuth flow, roles/permissions,
  webhooks, env vars, setup instructions, API reference, WebSocket auth,
  testing with mocked auth
- Update docs/config.md — add gnexus-auth OAuth env vars table
- Update docs/api.md — add /auth/*, /admin/*, /webhooks/gnexus-auth endpoints
- Update docs/index.md — add auth.md to file map
- Update docs/sessions.md — document user_id column and list_all filtering
- Update docs/memory.md — document user_id scoping in facts and summaries

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

Use gemma4 cloud model by default

Comprehensive documentation update ...

- websocket.md: add heartbeat, session_sync, replay_start/end, planning_status,
  plan_ready (with is_subagent), stream_end extra fields, context_compressed summary,
  updated _AgentRun.events replay buffer, corrected reconnect section
- sessions.md: add name, planning_logs fields; message flags (is_plan, is_compression,
  is_summary, thinking); set_name store op; debug endpoints section
- api.md: full rewrite — add generate-name, planning, file download endpoints;
  all missing WS events; correct message field table with is_plan/is_compression
- tools.md: update user tools list with all current tools
- index.md: fix profiles list (smart_home → developer)
- CLAUDE.md: add Documentation section with table of all docs files
- NAVI.md: add architecture.md entry, improve websocket description

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

docs: add profile_switched WS event and switch_profile flow ...

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

Add API reference documentation ...

Covers: REST endpoints (health, profiles, tools, sessions, files,
messages), WebSocket protocol (all event types, client→server format,
typical event sequences), error codes.

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