Introduce ClawdCursorHost (host IPC) and macOS native helper enhancements

[AmrDab]

Motivation

• Centralize macOS TCC permissions under a single bundled app identity (ClawdCursor.app) and provide a long-lived host process to own IPC and permission-sensitive operations.
• Enable richer native desktop control (smooth mouse moves/drags and screenshots) while avoiding unbundled-binary TCC issues on macOS.

Description

• Add a new host executable ClawdCursorHost with a small HTTP IPC server (127.0.0.1:<port>) and token auth, and register it in Package.swift and the app bundle (Info.plist).
• Update build flow (native/build.sh) to include ClawdCursorHost in the ClawdCursor.app bundle and change the default run hint to open ClawdCursor.app.
• Extend the Swift helper (ClawdCursorHelper) with new JSON-RPC methods: moveMouse, dragMouse, and captureScreen (PNG base64 encoding), and add required imports (ImageIO, UniformTypeIdentifiers).
• Add Sources/ClawdCursorHost/main.swift implementing the host listener, health/status endpoints, and proxying JSON-RPC POST /rpc to clawdcursor-helper when authorized.
• Rework Node-side native integration (src/native-helper.ts) to prefer communicating with the host IPC (/health, /status, /rpc), add utility functions (isHostRunning, ensureHostAppRunning, stopHostApp, token management), and provide fallback behavior controlled via CLAWDCURSOR_ALLOW_MAC_HELPER_FALLBACK.
• Wire the native helper into the desktop stack: src/native-desktop.ts now uses the native helper for captures, mouse moves/drags, typing and key presses on macOS when available; src/index.ts, src/doctor.ts, and src/readiness.ts updated to ensure the host is running and to reference ClawdCursor in user-facing messages.
• Add helper path resolution utilities and tighten permission-check behavior to prefer the host status endpoint before falling back to bundled permission-check binary.
• Update native/README.md to document the new ClawdCursorHost IPC endpoints and workflow.

Testing

• Built native Swift targets via the updated build script (./native/build.sh which runs swift build -c release) and confirmed ClawdCursor.app artifacts were produced successfully.
• Compiled the TypeScript codebase (npm run build) to ensure updated imports and types pass compilation.
• Performed basic host sanity checks by starting ClawdCursorHost and verifying GET /health and GET /status return expected JSON (local smoke tests succeeded).

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Codex Task