feat(cli): launch cursor/copilot-vscode and desktop app wrappers

[SachaMorard]

Summary

• Add public edgee launch cursor and edgee launch copilot-vscode (alias vscode-copilot) that delegate to the hidden relay for app targets.
• Canonicalize relay targets so copilot-vscode is the VS Code surface and bare copilot stays reserved for a future Copilot CLI.
• Extend edgee alias so one command installs both CLI shims and desktop app wrappers:
  • CLI (claude, codex, …) — PATH shims / shell aliases (unchanged)
  • Apps (cursor, copilot-vscode) — platform launchers only if the host app is already installed
    • macOS: ~/Applications/<Name> (Edgee).app (opens Terminal + edgee launch …)
    • Linux: ~/.local/share/applications/edgee-*.desktop
    • Windows: Start Menu .lnk via PowerShell
• Document launch-target naming rules (target vs provider key vs transport) in crates/cli/src/commands/launch/README.md, and update root/AGENTS docs.

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test --all
• edgee launch --help lists cursor and copilot-vscode (not bare copilot)
• edgee launch vscode-copilot --help resolves to copilot-vscode
• edgee launch copilot fails with a suggestion toward copilot-vscode
• Smoke: edgee launch cursor / edgee launch copilot-vscode start the relay and spawn the app (quit any running Cursor/VS Code first)
• edgee alias --help lists cursor and copilot-vscode
• With Cursor installed: edgee alias cursor creates ~/Applications/Cursor (Edgee).app (macOS) or the OS equivalent
• Without VS Code: edgee alias copilot-vscode prints skipped (host app not found)
• edgee alias remove cursor removes the wrapper
• edgee alias (all) still installs CLI shims and only adds app wrappers when hosts are present