Audit and fix docs/ for accuracy against current codebase ...

Package A (API + WebSocket + Sessions):
- api.md: add missing endpoints (health/embed, auth/status, agents/prompts,
  agents/mcp_servers, sessions/content, 7 admin endpoints). Fix response
  schemas, auth requirements, query params. Update path formats.
- websocket.md: fix planning_status.phase type (int 1|2|3), add metadata
  to tool_call, message_index to stream_end, context_tokens/max_context_tokens
  to context_compressed.
- sessions.md: fix context_compression_threshold default (0.80→0.70),
  add list_page method, add metadata to Message flags.

Package B (Config + Profiles + Tools + Agent + Memory):
- config.md: remove stale ANTHROPIC_API_KEY description, add 12 missing
  env vars (embedding, web search, terminal_user_allowed_commands,
  context_providers_dir, gnauth fields, output_reserve_tokens).
  Fix OPENAI_BASE_URL type.
- profiles.md: fix max_iterations default (20→10), add top_k/top_p/num_thread,
  is_admin_only, context_providers, mcp_servers, subagent_think_enabled.
  Clarify subagent_tools fallback and step_validation_enabled.
- tools.md: replace 3 separate memory tools with unified `memory`, add
  `mcp_status`.
- agent.md: fix run_ephemeral return type (str→tuple), clarify DB reads.
- memory.md: fix search_facts/get_all_facts param order, fix MemoryStore
  init description.

236 tests passing.

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

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>

Add backend documentation ...

10 markdown files covering all backend subsystems: architecture,
agent loop, tool system, sessions, WebSocket protocol, profiles,
memory, config, and API reference. Structured for AI readability
with a single entry point (docs/index.md) and cross-references.

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