feat: add custom shortcuts and multichannel packaging

[JacobOptimiza]

Summary

This PR adds the reviewed multichannel distribution and custom project commands while keeping DevNav as the native PowerShell 7 workspace navigator.

Included

1. Shift+1…Shift+9 custom project commands

   • Persistent aliases and commands for the highlighted project.
   • PowerShell configuration helpers and F1 help integration.

2. npm/Bun/pnpm/Yarn bootstrap packaging

   • Explicit bootstrap package with SHA-256 verification.
   • No postinstall scripts or runtime dependencies.

3. Scoop portable packaging

   • x64/ARM64 portable payloads and Scoop manifest template.
   • Scoop-managed installations delegate updates to scoop update devnav.

4. Release, CI and documentation support

   • Shared version and release payload validation.
   • Packaging tests, PowerShell module manifest, documentation and troubleshooting updates.

Important distribution notes

• Source version remains 0.9.7 intentionally.
• npm/Scoop publishing is blocked for versions <= 0.9.7.
• The first multichannel release will use the next appropriate release version.
• npm first publication and Scoop bucket bootstrap still require manual setup.
• The current upstream WinGet PR is untouched.

Testing

• cargo fmt --all -- --check — PASS
• cargo check --workspace --all-targets — PASS
• cargo clippy --workspace --all-targets -- -D warnings — PASS
• cargo test --workspace — 37/37 PASS
• cargo deny check — PASS
• cargo machete — PASS
• cargo audit — PASS
• PowerShell validation — PASS
• Pester — 24/24 PASS
• npm tests — 11/11 PASS
• Node 22/24/26 compatibility — PASS
• npm pack exact allow-list — PASS
• git diff --check — PASS

No merge, tag, release, npm publish or Scoop bucket creation is included in this PR.