Make server I/O non-blocking; update docs ...

- Wrap all heavy filesystem ops in asyncio.to_thread: filesystem tool
  (read/write/append/list/find/info/move/delete/query/smart_edit),
  image_view (read_bytes), share_file (shutil.copy2), write_tool
  (write_text, _register_user_tool), session_files (shutil.rmtree,
  iterdir), sessions upload endpoint (sync open/write → to_thread)
- Make delete_session_dir async; update its caller in sessions.py
- docs/config.md: fix wrong defaults (threshold 0.70, keep_recent 8),
  remove phantom SESSION_FILES_TTL_HOURS, add LLM timeouts, DATABASE_URL,
  PUBLIC_URL, Gmail, CONTEXT_SUMMARY_MAX_TOKENS sections
- docs/profiles.md: add missing tool_developer profile to table
- android-client: add WebView remote debugging; remove unused toolbar menu
- Remove stale helper scripts and test files

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

Add self-extension tool system: write_tool, list_tools, tool_manual ...

- loader.py: module-level format (name/description/parameters/execute)
  preferred, class-based as fallback; isolated errors per file
- write_tool: validates + writes tools/name.py, reloads registry,
  adds to tools/enabled.json in one call
- list_tools: live tool list from registry (prevents hallucination)
- tool_manual: serves manuals/*.md or auto-generates from schema
- reload_tools: hot-reload without server restart
- registry: registry injection pattern for tools that need it;
  _builtin_names set to guard against reload overwriting builtins

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