SSH connection pooling: per-session, 20-minute TTL ...

- Pool keyed by session_id:host:port:username — parallel sessions share
  no state even when targeting the same server
- Per-key asyncio.Lock prevents concurrent connection creation races
- TTL (20 min) and is_closing() checked on every access; expired/closed
  connections are evicted and replaced transparently
- On disconnect error during command execution: evict + retry once with
  fresh connection
- current_session_id ContextVar (set by Agent before tool calls) is read
  in ssh_exec to build the pool key without changing tool signatures

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

Wire self-extension tools into all profiles; improve tool descriptions ...

All profiles now include write_tool, list_tools, tool_manual, reload_tools.
User tools from enabled.json merged in at runtime via Agent._tool_list().
Built-in tool descriptions rewritten to be more LLM-actionable.

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

ssh_exec: accept credentials directly as tool parameters ...

host, username, password, port, key_path are now first-class parameters.
No config file needed — user can pass creds in the chat message.
Ad-hoc connections skip host key verification by default.
Named connections in ssh_hosts.json still work as a shortcut.

Fix SSH password auth: disable key lookup when password is configured ...

asyncssh tried ~/.ssh/* keys before the password, causing PermissionDenied
on hosts that only accept password auth. Now when 'password' is set and no
'client_keys', key auth is disabled entirely.

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