fix(mcp): connect servers immediately after dashboard install

[elliottophellia]

Summary

Fixes newly added MCP servers remaining unavailable until the user manually clicks Refresh.

Both dashboard installation paths now run the shared MCP refresh lifecycle after saving and reloading configuration:

• Manual Add server
• MCP Browse installation

Deleting a server also refreshes the manager immediately, removing its registered tools and closing obsolete transports.

Implementation

Replaces the background Manager.Connect calls with the serialized Manager.Refresh lifecycle. This ensures that, before the mutation response returns:

• Configured servers are connected
• Connection errors are reflected in dashboard status
• MCP tools are published to the agent registry
• Removed tools are unregistered
• Replaced transports are closed

Verification

• go test ./...
• go test -race ./internal/server ./internal/mcp
• bun run typecheck
• bun test
• Focused tests for manual add, Browse install, deletion, and tool registry replacement