feat(cli): migrate console calls to debugLogger and stdioHelpers (M3 Phase 7-9)

Route CLI console.* calls to structured logging:
- Debug/internal diagnostics → debugLogger (logfile)
- User-facing output → writeStdoutLine/writeStderrLine/clearScreen (stdioHelpers)
- Add stdioHelpers.ts with writeStdoutLine, writeStderrLine, clearScreen
- Migrate pre-session files (gemini.tsx, sandbox.ts, config.ts) to stdioHelpers
- Migrate extension/MCP commands to stdioHelpers
- Migrate non-interactive session/control to debugLogger
- Migrate UI hooks and components to debugLogger

packages/cli/src/acp-integration/session/SubAgentTracker.ts

@@ -17,6 +17,7 @@ import type {
 import {
   SubAgentEventType,
   ToolConfirmationOutcome,
+  createDebugLogger,
 } from '@qwen-code/qwen-code-core';
 import { z } from 'zod';
 import type { SessionContext } from './types.js';
@@ -24,6 +25,8 @@ import { ToolCallEmitter } from './emitters/ToolCallEmitter.js';
 import { MessageEmitter } from './emitters/MessageEmitter.js';
 import type * as acp from '../acp.js';
 
+const debugLogger = createDebugLogger('ACP_SUBAGENT_TRACKER');
+
 /**
  * Permission option kind type matching ACP schema.
  */
@@ -135,7 +138,7 @@ export class SubAgentTracker {
           invocation = tool.build(event.args);
         } catch (e) {
           // If building fails, continue with defaults
-          console.warn(`Failed to build subagent tool ${event.name}:`, e);
+          debugLogger.warn(`Failed to build subagent tool ${event.name}:`, e);
         }
       }
 
@@ -250,7 +253,7 @@ export class SubAgentTracker {
         await event.respond(outcome);
       } catch (error) {
         // If permission request fails, cancel the tool call
-        console.error(
+        debugLogger.error(
           `Permission request failed for subagent tool ${event.name}:`,
           error,
         );