upgrade/setup must migrate MCP transport and bootstrap BrainBarDaemon

[EtanHey]

Problem

The packaged reconnecting MCP bridge and split BrainBarDaemon architecture exist, but an upgraded host can retain both:

1. a user MCP config that invokes raw socat STDIO UNIX-CONNECT:/tmp/brainbar.sock;
2. no com.brainlayer.brainbar-daemon LaunchAgent.

On the repaired M1:

• BrainLayer and the app bundle were 1.5.1;
• the cask receipt remained 1.4.0,1;
• BrainBar.app ran, but the daemon label was absent;
• the stale socket returned ECONNREFUSED;
• Claude reported a configured server with no usable tools.

Installing the signed bundled daemon plist restored the socket immediately.

Expected

Upgrade/setup should idempotently converge user state:

• install/bootstrap the bundled daemon LaunchAgent;
• migrate known raw-socat MCP entries to brainlayer-mcp-stdio-bridge;
• preserve unrelated MCP config;
• verify initialize and tools/list.

Acceptance

• Upgrade test starts from a legacy raw-socat config and missing daemon plist.
• Re-running setup is idempotent.
• A stale/unbound socket produces a loud disconnected state, not silent tool absence.
• No sudo is required when the signed app already exists and is user-readable.