feat(minimald): lifecycle management (run --detach, status, stop) - #435

On Linux, check if the daemon UDS is connectable before each command.
If not, spawn `minimald run` as a detached background process (setsid +
null stdio) and poll the UDS until it becomes available (4s timeout).

Also fixes resolve_socket_path() to match minimald's listen_on() on
Linux ($XDG_STATE_HOME/minimal/providers/local-0/ssh.sock), which was
previously broken — it only worked on macOS via minvmd.

No state machine or state.toml — just socket polling. The lifecycle
management PR (#435) can layer richer state tracking on top later.

…destroy) (#434)

* feat(minimal2): implement client interface with SSH transport (#159)

- Add CLI subcommands: activate, attach, destroy, dash (fzf picker stub)
- Implement SSH client transport over UDS to minimald
- Wire oneshot RPC calls for ls (list sessions), activate (create session)
- Add exec_in_session for non-interactive command execution in sessions
- PTY interactive shell is blocked on daemon PTY support (exec.rs:650-654)
- Update Cargo.toml with minimald-rpc, russh, sessions, serde_json deps

* feat(minimal2): add --raw flag and 'dash' fzf session picker (#159)

- ls --raw: outputs one session ID per line for fzf piping
- minimal dash: interactive fzf picker that chains into attach
- Falls back to plain table if fzf is not installed
- Update implementation plan with Phase 5 details

* feat(minimal2): interactive attach via ssh ProxyCommand (#159)

Implement twitchyliquid64's suggestion: shell out to ssh for interactive
PTY attachment instead of reporting it as unsupported. The daemon's
shell_request handler already mints PTY-backed session shells, so we
avoid reimplementing termios/PTY management by deferring to openssh.

Adds a hidden `proxy` subcommand that pipes stdio to the daemon UDS,
used as ssh's ProxyCommand so we don't depend on socat or nc being
installed. Also fixes pre-existing fmt/clippy failures.

* feat(minimal2): wire up destroy command via DestroySession RPC (#159)

Wire cmd_destroy to the DestroySession RPC added in #462. Resolves the
session by UUID or name via GetSessionRecord (matching cmd_attach), then
issues the destroy RPC and prints confirmation.

* refactor(minimal2): migrate attach --command to ssh shell-out (#159)

Per reviewer feedback, exec_in_session used the daemon's old exec codepath
which doesn't hit the sessions module. Remove it entirely and shell out
to ssh for both interactive and --command attachment — ssh handles
termios/PTY reconfiguration and the daemon's shell_request handler
mints the session shell. exec_request remains on the daemon side for
git-receive-pack and vscode remote only.

* feat(minimal2): auto-spawn minimald on Linux (#159)

On Linux, check if the daemon UDS is connectable before each command.
If not, spawn `minimald run` as a detached background process (setsid +
null stdio) and poll the UDS until it becomes available (4s timeout).

Also fixes resolve_socket_path() to match minimald's listen_on() on
Linux ($XDG_STATE_HOME/minimal/providers/local-0/ssh.sock), which was
previously broken — it only worked on macOS via minvmd.

No state machine or state.toml — just socket polling. The lifecycle
management PR (#435) can layer richer state tracking on top later.

* fix(minimal2): thread --minimal-dir through auto-spawn

Auto-spawn was checking the default UDS path instead of the --minimal-dir
override, causing it to fail when the daemon was already running with a
custom state dir. Also pass --minimal-state-dir to the spawned minimald
so it listens on the same path we're polling.

E2E verified: ls, activate, attach --command, destroy (by UUID and
name), auto-spawn (default and --minimal-dir paths).

* refactor(minimal2): remove temporary dash/fzf picker

Remove the `dash` subcommand, `ls --raw` flag, and `LsArgs` struct.
These were temporary scaffolding for an fzf-based session picker — a
proper TUI will be built later. Net -125 lines.

* revert(minimal2): add back ls --raw flag

--raw has standalone value for scripting (e.g. `minimal ls --raw | fzf`),
independent of the removed dash subcommand.

* style(minimal2): add missing blank line between functions

* feat(minimald,minimal2): detect starting daemon via PID file

minimald now writes a PID file at startup. The minimal2 auto-spawn logic
checks this file before spawning: if the PID is alive the daemon is
already starting (e.g. spawned concurrently), so it waits for the UDS
rather than spawning a duplicate. The spawn path uses Child::try_wait
to detect a crash during startup and fail fast instead of exhausting
the 4s timeout.

Addresses review feedback on #434.