refactor: streamline agent orchestration and add blockquote styling

- Simplify agent-prompt.md with clearer delegation rules and workflow
- Add blockquote markdown styling to message component
- Update agent type to support both claude and codex agents

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/server/src/server/acp/mcp-server.ts

@@ -215,7 +215,7 @@ export async function createAgentMcpServer(
             status: z.string(),
             createdAt: z.string(),
             lastActivityAt: z.string(),
-            type: z.literal("claude"),
+            type: z.enum(["claude", "codex"]),
             sessionId: z.string().nullable(),
             error: z.string().nullable(),
             currentModeId: z.string().nullable(),
@@ -264,7 +264,7 @@ export async function createAgentMcpServer(
             status: z.string(),
             createdAt: z.string(),
             lastActivityAt: z.string(),
-            type: z.literal("claude"),
+            type: z.enum(["claude", "codex"]),
             sessionId: z.string().nullable(),
             error: z.string().nullable(),
             currentModeId: z.string().nullable(),