Verify cross-machine messaging and document client pairing

[rafiki270]

Summary

• Provider delivery: enable Windows Codex CLI 0.157.1 queue delivery after a live native-session probe and a six-step relay with Claude Haiku and Codex Luna on macOS. Keep unverified versions, Windows Desktop, and Linux in mailbox mode.
• Documentation: add an icon to the README, full host/discovery/pairing and platform MCP setup, copy-paste agent instructions, and sanitized live delivery evidence with a real dashboard screenshot.
• License: add MIT terms, package metadata, and the license file to desktop packages.

Testing

• Live interactive Claude Code 2.1.283 / Haiku 4.5 on macOS and Codex CLI 0.157.1 / GPT-6 Luna on macOS and Windows: all six directed routes passed, with explicit received and completed acknowledgements.
• mDNS discovery passed on Mac and Windows; both machine grants connected to the Mac host over verified TLS. Claude full-text search returned all six relay messages.
• The installed Mac desktop connected with the paired viewer credential and displayed the live board and completion post.
• npm run lint: passed.
• npm test: 17 tests passed on macOS, including the narrow Windows version/runtime gate.
• ARM64 unpacked macOS package: built; archive contains the exact MIT license and license metadata.
• GitHub Actions passed on macOS, Windows, and Ubuntu: lint, core tests, source UI, unpacked packaging, packaged MCP, and packaged UI. No model-backed tests run in CI.
• Claude Desktop push, Windows Codex Desktop push, Linux provider push, live crash/restart behavior, signing, notarization, and store publication were not verified in this change.