refactor(core): 更新内置命令的 agent 配置

- /test, /fix, /commit 使用 general agent
- /explain 使用 explore agent (更适合代码解释)
- /help 使用 guide agent (更适合帮助信息)

packages/core/src/commands/builtin/index.ts

@@ -127,7 +127,7 @@ Provide a clear, structured explanation that includes:
 2. How it works - Step by step breakdown
 3. Key concepts - Important patterns or techniques used
 4. Examples - Practical usage examples if applicable`,
-  agent: 'general',
+  agent: 'explore',
   subtask: false,
   source: 'builtin',
 };
@@ -178,7 +178,7 @@ Topic: $ARGUMENTS
 
 If a specific command is mentioned, provide detailed help for that command.
 Otherwise, list all available commands with their descriptions.`,
-  agent: 'general',
+  agent: 'guide',
   subtask: false,
   source: 'builtin',
 };