P1: Upgrade channels (stable/beta) + pinned version + target version install

[Kinin-Code-Offical]

[Kinin-Code-Offical]

Plan:

• Extend update checks to support channels (stable/beta) and explicit target version selection.
• Add CLI options for --channel, --version (target), and config pinning.
• Update release selection logic to fetch latest for channel or a specific tag.

Risks:

• Incorrect version resolution could skip updates or pick wrong assets.

Tests:

• npm ci
• npm run lint
• npm test
• npm run build

[Kinin-Code-Offical]

PR merged: #36
Merge commit: d5c7c69