Ship the localhost CLI with the app and connect coding agents (MCP + skill) in one click #35

Today localhost mcp isn't in the release downloads. Users have to build it from source (cargo install), add it by hand to each agent's MCP config, and copy skills/localhost-mcp/SKILL.md themselves. A hand-built binary also goes stale: one built before #31 speaks core protocol v4 and can't connect to a 0.2.0 core (v5).

Goal: installing the app should be enough to use localhost from Claude Code, Cursor and Codex.

Scope

1. Bundle the localhost CLI with the app on macOS (inside the .app), Windows (NSIS install dir) and Linux (.deb/.rpm/AppImage), always the same version as the app and the core. Offer to put it on PATH (e.g. a symlink in ~/.local/bin or /usr/local/bin on macOS/Linux, the user PATH on Windows), with a clear explanation and an undo.
2. "Connect your agents" screen, shown in first-run onboarding and available in Settings (plus a command palette entry):
   • Detect installed clients: Claude Code, Cursor and Codex (and any other client whose MCP config location is officially documented).
   • For each one, show exactly what will change (file path plus the entry to be added), then add or update the localhost MCP server entry pointing at the bundled binary, and install the localhost-mcp skill into that client's documented skills folder where one exists.
   • Show per-client status (connected / not installed / config points at an outdated or missing binary), and offer Disconnect, which removes only our entries.
   • Never touch another app's config without the user clicking; never overwrite unrelated entries; back up a config file before the first edit. Must be idempotent.
3. Keep it current across updates: the bundled binary updates with the app (Auto-update: detect new releases and update in-app #29/Detect new releases and update in-app on macOS, Linux and Windows #31). If an agent's config points at a different localhost binary (e.g. ~/.cargo/bin/localhost), flag it and offer to repoint it.
4. Docs: update /agents, docs/mcp and docs/skills (from Tell users about 0.2.0's features on the landing page, docs, README, and a new page about AI agents #33/Tell users about 0.2.0's agents, updates and platforms #34) and the README so the one-click path comes first and the manual setup stays as a fallback.

Acceptance

• A fresh install on each OS can connect Claude Code, Cursor and Codex from the app without a terminal, and the agent can list/start/stop Services through the shared core.
• Reconnecting, disconnecting and updating leave other config entries untouched (covered by tests on sample config files).
• The release workflow ships and signs the bundled binary on all platforms.
• Only verified, officially documented config and skill locations are used for each client; any client without one is reported, not guessed.
• One PR against main, not merged without Marcel's approval.