feat(app): add pairing to server settings - #49700

Summary

• Move Pairing from client settings into each connected server’s settings.
• Support direct connection details and server-owned Tailscale Serve management for HTTP and WSL servers.
• Keep Pairing visible but disabled for SSH servers with an explanatory tooltip.

Before / After

Settings at 1200 × 900 in dark mode, using the same two-server fixture and pairing state.

Before	After

Validation

• bun run check
• bun typecheck && bun test test/pairing.test.ts test/process.test.ts from packages/server
• bun typecheck && bun test src/settings/search-results.test.ts from packages/app
• Fixture-driven UI comparison at 1200 × 900 in dark mode

Stack

• Depends on feat(desktop): add local device pairing #49291.