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/web/public/app.js

@@ -3004,7 +3004,7 @@ class CodemanApp {
           <span class="tab-status ${status}" aria-hidden="true"></span>
           <span class="tab-info">
             <span class="tab-name-row">
-              ${mode === 'shell' ? '<span class="tab-mode shell" aria-hidden="true">sh</span>' : mode === 'opencode' ? '<span class="tab-mode opencode" aria-hidden="true">oc</span>' : mode === 'codex' ? '<span class="tab-mode codex" aria-hidden="true">cx</span>' : ''}
+              ${mode === 'shell' ? '<span class="tab-mode shell" aria-hidden="true">sh</span>' : mode === 'opencode' ? '<span class="tab-mode opencode" aria-hidden="true">oc</span>' : mode === 'codex' ? '<span class="tab-mode codex" aria-hidden="true">cx</span>' : mode === 'gemini' ? '<span class="tab-mode gemini" aria-hidden="true">gm</span>' : ''}
               <span class="tab-name" data-session-id="${id}">${(() => { const p = parseSessionPrefix(name); return p && p.suffix ? '<span class="tab-prefix">' + escapeHtml(p.prefix) + '</span><span class="tab-suffix">: ' + escapeHtml(p.suffix) + '</span>' : escapeHtml(name); })()}</span>
               <span class="tab-detached-badge" aria-hidden="true">detached</span>
             </span>
@@ -3988,7 +3988,9 @@ class CodemanApp {
         ? 'Kill Tmux & OpenCode'
         : session.mode === 'codex'
           ? 'Kill Tmux & Codex'
-          : 'Kill Tmux & Claude Code';
+          : session.mode === 'gemini'
+            ? 'Kill Tmux & Gemini'
+            : 'Kill Tmux & Claude Code';
     }
 
     document.getElementById('closeConfirmModal').classList.add('active');