fix(workflows): replace even/odd versioning with SemVer -rc.N suffixes

[WilliamBerryiii]

Pre-release versioning previously relied on an even/odd minor version convention to distinguish stable from pre-release builds across the CI/CD pipeline. This scheme was fragile, produced version collisions when both pipelines targeted the same minor, and was redundant — the VS Code Marketplace determines channel placement via the --pre-release flag, not version number inspection. This PR replaces the entire even/odd scheme with standard SemVer -rc.N pre-release suffixes.

Changes

Pre-release version computation

The core versioning logic in prerelease.yml was the most significant change, replacing arithmetic parity checks with conventional commit analysis.

• Rewrote version computation in prerelease.yml to use conventional commit bump rules — breaking changes bump major, new features bump minor, all others bump patch
• Added feature commit detection (HAS_FEAT) alongside existing breaking change detection for accurate minor version bumps
• Fixed an unanchored BREAKING[ -]CHANGE regex to ^BREAKING[ -]CHANGE: to prevent false positives from commit body content
• Appended -rc.N suffix using git rev-list --count as the RC number, producing versions like 3.1.0-rc.5

Validation and channel routing

The remaining five workflow files enforce the -rc.N convention at their respective gates.

• Updated prerelease-release.yml to extract and validate -rc.N suffixes from PR titles instead of checking minor version parity
• Replaced auto-detection in extension-publish-prerelease.yml — queries gh release list with isPrerelease filter instead of deriving an odd minor from the latest stable tag
• Updated extension-publish.yml stable channel guard to reject -rc.N versions rather than requiring even minor numbers
  • The existing format regex ^[0-9]+\.[0-9]+\.[0-9]+$ provides defense-in-depth by rejecting -rc.N before the explicit check
• Simplified main.yml post-release reset to "${MAJOR}.$((MINOR + 1)).0-rc.0", removing the ODD_MINOR arithmetic and modulo guard
• Cleaned up channel labels in extension-publish-marketplace.yml from "Pre-Release (ODD minor)" to "Pre-Release"

Type of Change

• Bug fix (non-breaking change fixing an issue)
• GitHub Actions workflow

Related Issues

None

Testing

• All six workflow files pass YAML lint validation (npm run lint:yaml)
• Verified the --pre-release flag on vsce publish controls VS Code Marketplace channel placement, confirming even/odd was never used by the marketplace
• Traced each pipeline path end-to-end: pre-release computation, pre-release validation, pre-release extension publish, stable extension publish, and post-release reset

Checklist

Required Checks

• Files follow existing naming conventions
• Changes are backwards compatible (if applicable)

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None