BREAKING CHANGE: Remove legacy @mosaic/cli fallback from update-checker.
The updater now targets only @mosaic/mosaic — legacy package compatibility
is out of scope per approved breaking change.
- update-checker.ts: remove LEGACY_PKG, INSTALLED_PACKAGE_ORDER, candidate
iteration, and cache key comparison. Single query for @mosaic/mosaic only.
- update-checker.test.ts: remove legacy fallback and cross-contamination
tests. Add test asserting no @mosaic/cli queries are made.
- pr-merge.sh: add --repo and --login flags to tea merge command; resolve
OWNER/REPO before case block.
- issue-close.sh: add --repo and --login flags to tea issue commands;
resolve OWNER/REPO after detect_platform.
- pr-ci-wait.sh: no changes needed (uses curl, not tea).
- detect-platform.sh: no changes needed (provides get_repo_owner/name).
Ref: #387
