Improve Windows desktop client detection and Codex CLI handling

[bbooxxyy]

Summary

• Detect Microsoft Store/AppX desktop clients and launch them through their registered application identity.
• List Codex CLI and Codex Desktop independently while sharing Codex provider, MCP, and configuration state.
• Detect the public CLI bundled with Codex Desktop and launch it in a terminal when no standalone CLI is on PATH.
• Migrate existing client ordering so Codex Desktop appears immediately after Codex CLI.
• Bump AgentDock to 0.1.46.

Verification

• Rust unit tests: 177 passed, 0 failed, 3 ignored
• Frontend tests: 9 passed
• cargo clippy --all-targets: passed with existing warnings
• Production UI build: passed
• Windows x64 NSIS bundle: built and architecture/version verified