fix(web): show connecting state on launching agent during Auto Run launch

[chr1syy]

Summary

Follow-up to RunMaestro#946 addressing Gap 1 from the post-review notes (https://gist.github.com/chr1syy/67630166ff5217a97d7b1fad91201f3b).

On web/mobile, the launching agent's status indicator stayed green throughout an Auto Run launch (worktree-toggle or otherwise), leaving users without visual confirmation that the launch actually fired. Desktop already flips the indicator to busy/connecting during the spawn.

• Switch `launchAutoRun` to use `sendRequest`, returning `Promise` so callers can await `configure_auto_run_result` (worktree forwarding from feat(web): add Run-in-Worktree toggle to mobile AutoRun launch RunMaestro/Maestro#946 is preserved).
• In `mobile/App.tsx`, optimistically flip the launching session's `state` to `connecting` (pulsing orange `StatusDot`) before sending; revert to the captured pre-launch state if the server reports failure. Subsequent `session_state_change` broadcasts overwrite the optimistic value when the agent actually transitions to busy.
• Expose `setLocalSessionState` on the public `useSessions` return so other consumers can drive the same optimistic-update pattern.

Test plan

• `npx tsc -p tsconfig.lint.json` clean for touched files (pre-existing repo errors are environmental and unrelated)
• ESLint clean on touched src files
• Prettier clean on all touched files
• `useAutoRun.test.ts` — 10 cases (worktree forwarding + Promise success / server-error / rejection / missing-success-field; loadGitBranches and listWorktrees retained)
• `useSessions.test.ts` — 77 cases including 3 new for `setLocalSessionState` (optimistic update, server-broadcast overwrite, unknown-id no-op)
• `messageHandlers.test.ts` — 105 cases pass (server-side `configure_auto_run` flow unchanged)
• Manual: launch an Auto Run on mobile/web with the worktree toggle off — indicator briefly turns pulsing orange, then yellow as the agent processes
• Manual: launch with worktree toggle on — same behavior; indicator transitions through connecting → busy as the worktree spawns and dispatches

🤖 Generated with Claude Code

[chr1syy]

Reopening on upstream RunMaestro/Maestro so it's visible alongside PR RunMaestro#946.