perf(pi): reuse tau rpc for command auto-replies

src/agents/index.ts

@@ -1,5 +1,6 @@
 import { claudeSpec } from "./claude.js";
 import { codexSpec } from "./codex.js";
+import { geminiSpec } from "./gemini.js";
 import { opencodeSpec } from "./opencode.js";
 import { piSpec } from "./pi.js";
 import type { AgentKind, AgentSpec } from "./types.js";
@@ -7,6 +8,7 @@ import type { AgentKind, AgentSpec } from "./types.js";
 const specs: Record<AgentKind, AgentSpec> = {
   claude: claudeSpec,
   codex: codexSpec,
+  gemini: geminiSpec,
   opencode: opencodeSpec,
   pi: piSpec,
 };