fix(dashboard): hoist claude_argv to Bottle ABC so smolmachines pane attach works

Launching a smolmachines agent from the dashboard inside tmux
crashed with

  AttributeError: 'SmolmachinesBottle' object has no attribute
  'claude_docker_argv'

because the tmux pane-respawn path called
`bottle.claude_docker_argv(...)` directly — a method that only
existed on DockerBottle. The foreground-handoff path (curses
endwin → subprocess.run → restore) doesn't hit it; it goes
through `bottle.exec_claude` which is on the ABC.

- Move the argv builder onto the `Bottle` ABC as
  `claude_argv(argv, *, tty=True) -> list[str]`. Both backends
  implement it; both `exec_claude` impls collapse to
  `subprocess.run(self.claude_argv(argv, tty=tty), check=False)`.

- DockerBottle: rename `claude_docker_argv` → `claude_argv`,
  body unchanged.

- SmolmachinesBottle: extract the argv-building from
  `exec_claude` into `claude_argv`; the new method returns the
  full `smolvm machine exec --name … -- runuser -u node --
  claude …` argv. The `runuser` switch lives on the
  exec-framing prefix so the dashboard's
  `_build_resume_argv_with_fallback` split-at-"claude" trick
  keeps the UID switch when wrapping the claude tail in
  `sh -c "… --continue || …"`.

- Dashboard: drop the docker-specific wording — local + helper
  arg names `docker_argv` → `claude_argv`; docstrings on
  `_build_resume_argv_with_fallback`, `_build_split_pane_argv`,
  `_build_respawn_pane_argv` now say "backend-exec argv". The
  shell-fallback wrap is unchanged; the existing logic works
  for smolmachines because `claude` is still the marker token.

Tests:
- `tests/unit/test_smolmachines_bottle.py` (new): locks down
  the smolmachines argv shape — prompt-file flag injection,
  guest-env `-e K=V` forwarding, TTY toggle, runuser-precedes-
  claude invariant.
- `test_docker_bottle.py`: TestClaudeDockerArgv →
  TestClaudeArgv; method renames follow.
- `test_dashboard_active_agents.py`: docstring follow.

615 unit tests pass.

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

claude_bottle/backend/docker/bottle.py

@@ -28,15 +28,9 @@ class DockerBottle(Bottle):
         self._prompt_path = prompt_path_in_container
         self._closed = False
 
-    def claude_docker_argv(
+    def claude_argv(
         self, argv: list[str], *, tty: bool = True,
     ) -> list[str]:
-        """Return the full `docker exec` argv for running claude in
-        this bottle. Public so callers that want to spawn claude
-        somewhere other than the dashboard's foreground (e.g.,
-        `tmux split-window` / `tmux respawn-pane` from the dashboard
-        when `$TMUX` is set) can build on the same command without
-        duplicating the `--append-system-prompt-file` plumbing."""
         full_argv = list(argv)
         if self._prompt_path:
             full_argv.extend(["--append-system-prompt-file", self._prompt_path])
@@ -48,7 +42,7 @@ class DockerBottle(Bottle):
 
     def exec_claude(self, argv: list[str], *, tty: bool = True) -> int:
         return subprocess.run(
-            self.claude_docker_argv(argv, tty=tty), check=False,
+            self.claude_argv(argv, tty=tty), check=False,
         ).returncode
 
     def exec(self, script: str, *, user: str = "node") -> ExecResult: