Add MCP setup to the app menu

[pranc1ngpegasus]

Summary

• add Wisp → MCP Setup… and the ⌘, shortcut
• add a dedicated, single-instance setup window for enabling, disabling, and retrying the local MCP bridge
• let users copy the bundled executable path or ready-to-paste Claude and OpenCode configurations
• carry the active IPC address and optional token into copied configs, and warn when a non-loopback bridge has no token
• document the new setup flow

Why

The local MCP bridge was only discoverable from the library screen, while client registration still required manually finding the bundled wisp-mcp path. The new menu flow makes setup available regardless of the current transcript view or permission onboarding state without mutating recording state.

Validation

• cargo fmt --all -- --check
• git diff --check
• cargo check -p wisp-desktop --all-targets --features gpui/runtime_shaders
• cargo test --workspace --features gpui/runtime_shaders — 52 tests passed

The default GPUI Metal precompilation path could not be exercised locally because this machine does not have the Full Xcode metal tool; the runtime-shader build path compiled and passed the full workspace test suite.