ci: fix prospective release tag quoting

[rogerchappel]

Summary

• execute the release dry-run prospective-tag calculation from a YAML block so shell quoting is preserved
• regression-test the actual workflow command and confirm it passes v0.1.0 to the package tag validator
• retain prospective tag validation before the release checks

Commits

• test: execute prospective release tag command — extracts and executes the workflow shell block, verifies the exact accepted tag, and checks ordering
• ci: fix prospective release tag quoting — replaces the malformed escaped inline command with a valid shell block

Verification

• npm ci
• npm run release:check
• git diff --check origin/main...HEAD

All 27 tests, type checking, build, CLI smoke, and packed-package smoke passed locally.

[rogerchappel]

Automated merge note

Triage class: auto-merge

Summary: Fixes shell quoting for the prospective release-tag validation and adds regression coverage that executes the workflow command (2 files, +16/-2).

Checks run: GitHub Repository hygiene and Release dry run / dry-run completed SUCCESS; recorded worker verification: npm ci, npm run release:check, release-tag command regression, and git diff --check.

Rebased/CI-repaired: No.

Verified head SHA: 63a24a424e34a29d902e5bfa1a75db3bd12c6f66.