feat: add model selection for AI agents (claude, codex, gemini)

Add a new ModelSelector component that allows users to choose specific model variants for different AI agents. This includes:
- ModelSelector UI component with agent-specific model options
- Model parameter propagation through API, RPC, and spawning layers
- Support for auto model selection (default behavior)
- Localization strings for English and Chinese
- Type definitions for model options per agent

cli/src/api/apiMachine.ts

@@ -100,7 +100,7 @@ export class ApiMachineClient {
 
     setRPCHandlers({ spawnSession, stopSession, requestShutdown }: MachineRpcHandlers): void {
         this.rpcHandlerManager.registerHandler('spawn-happy-session', async (params: any) => {
-            const { directory, sessionId, machineId, approvedNewDirectoryCreation, agent, yolo, token, sessionType, worktreeName } = params || {}
+            const { directory, sessionId, machineId, approvedNewDirectoryCreation, agent, model, yolo, token, sessionType, worktreeName } = params || {}
 
             if (!directory) {
                 throw new Error('Directory is required')
@@ -112,6 +112,7 @@ export class ApiMachineClient {
                 machineId,
                 approvedNewDirectoryCreation,
                 agent,
+                model,
                 yolo,
                 token,
                 sessionType,

cli/src/modules/common/rpcTypes.ts

@@ -4,6 +4,7 @@ export interface SpawnSessionOptions {
     sessionId?: string
     approvedNewDirectoryCreation?: boolean
     agent?: 'claude' | 'codex' | 'gemini'
+    model?: string
     yolo?: boolean
     token?: string
     sessionType?: 'simple' | 'worktree'

cli/src/runner/run.ts

@@ -333,6 +333,9 @@ export async function startRunner(): Promise<void> {
           '--hapi-starting-mode', 'remote',
           '--started-by', 'runner'
         ];
+        if (options.model) {
+          args.push('--model', options.model);
+        }
         if (yolo) {
           args.push('--yolo');
         }