Add workspace dir + clean up junk from project root ...

- workspace/ — persistent dir for Navi's long-term files (scripts, notes,
  data); excluded from git, Navi instructed to use it instead of project root
- .gitignore: session_files/ and workspace/* added
- persona.txt: WORKSPACE section pointing Navi to workspace/
- Deleted scanner.py, network_scan_results.txt, targets.txt (Navi artifacts)

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

Update .gitignore: ignore tmp files and tool data files ...

Add .tmp, task_manager.json, tools/*_data.json (runtime data written
by user tools like user_notes). Remove brain_kb.py (broken syntax).

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

Persistent sessions and client module refactor ...

Server:
- SqliteSessionStore replaces InMemorySessionStore as default backend
- Sessions survive server restarts (stored in navi.db)
- DB_PATH configurable via .env

Client:
- Split monolithic app.js into ES modules:
  js/api.js    — REST calls
  js/ws.js     — WebSocket wrapper (WsClient class)
  js/chat.js   — message area DOM helpers
  js/sidebar.js — session list and header helpers
  js/app.js    — state, wiring, boot
- Active session persisted in localStorage — restored on page reload

Unrestricted terminal mode and SSH tool ...

- Terminal: TERMINAL_ALLOWED_COMMANDS=* (default) runs via shell,
  supports pipes, redirects, subshells; allowlist mode still available
- FS_ALLOWED_PATHS expanded to cover /home /etc /var /opt
- New ssh_exec tool: execute commands on remote hosts via asyncssh,
  supports named connections (ssh_hosts.json) and inline user@host
- ssh_hosts.json gitignored, ssh_hosts.json.example added as reference
- ssh_exec added to server_admin and smart_home profiles

Initial implementation of the agent system core ...

- FastAPI server with REST API and WebSocket streaming
- Modular LLM backend abstraction (Ollama implemented, OpenAI stub)
- Tool system: web_search (ddgs), filesystem, http_request, code_exec, terminal
- Agent profiles: smart_home, server_admin, secretary
- Tool-calling loop with concurrent tool execution
- In-memory session store with SessionStore ABC for future persistence
- Registry pattern for tools, profiles, and backends
- Orchestrator stub as foundation for multi-agent scenarios