fix: address PR review findings for Gemini run mode + Ralph todo-config

Gemini (PR #134) blockers:
- runGemini() now unwraps the {success,data} envelope: status check reads
  .data.available, quick-start reads data.data.sessionId (was reading the raw
  shape, so the Run-Gemini button could never start a session).
- setGeminiEnvVars() now uses the socket-scoped ${this.tmux()} setenv instead of
  bare tmux — Gemini/Google auth env vars were targeting the wrong tmux server
  and silently failing on every install.

Gemini parity polish:
- gemini tab-mode badge ('gm') + .tab-mode.gemini CSS; kill-dialog label
  'Kill Tmux & Gemini'; codeman doctor dependency-registry entry; export
  isGeminiAvailable from utils barrel; COLORTERM=truecolor + unset NO_COLOR;
  add gemini to isAltScreenStripMode (Ink TUI, repaints inline like Codex/Claude).
- Revert 4 system-routes.test.ts envelope assertions weakened to
  (body.message ?? body.error) back to (body.success === false).
- Add a runGemini() vm-sandbox test that drives the envelope path end-to-end.

Ralph todo-config (PR #135): maxTodos/todoExpirationMinutes are now persisted
and read back — surfaced via the loopState getter (RalphTrackerState) into
toState()/SSE broadcast and restored in restoreState(), mirroring maxIterations.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ralph-tracker.ts

@@ -1059,6 +1059,10 @@ export class RalphTracker extends EventEmitter {
       planVersion: this.planTracker.planVersion,
       planHistoryLength: this.planTracker.getPlanHistory().length,
       completionConfidence: this._lastCompletionConfidence,
+      // Surface the live todo-config so it persists (toState) and reads back into
+      // the Session Options modal (broadcast) — mirrors maxIterations round-trip.
+      maxTodos: this._maxTodos,
+      todoExpirationMinutes: this.todoExpirationMinutes,
     };
   }
 
@@ -2345,6 +2349,12 @@ export class RalphTracker extends EventEmitter {
       ...loopState,
       enabled: loopState.enabled ?? false,
     };
+    // Restore the per-session todo-config into the live fields used by the hot
+    // paths (eviction cap + expiry). Setters ignore non-positive values.
+    if (typeof loopState.maxTodos === 'number') this.setMaxTodos(loopState.maxTodos);
+    if (typeof loopState.todoExpirationMinutes === 'number') {
+      this.setTodoExpirationMinutes(loopState.todoExpirationMinutes);
+    }
     this._todos.clear();
     for (const todo of todos) {
       this._todos.set(todo.id, {