fix(cli): enforce fingerprint-safe install and sync

[XiaoSeS]

Summary

• validate the extracted install snapshot against the fingerprint returned by resolve before replacing files or writing inventory
• make namespace sync decide from semantic version order plus fingerprint
• block same-version content drift, automatic downgrade, and unorderable versions with validation exit code 6
• keep hard remote guards effective under local edits, --force, and --check
• share the strict version comparator with upgrade and document the behavior

Behavior

Local vs remote	Result
same version + same fingerprint	up-to-date
remote version is newer	update-available, even when content is identical
same version + different fingerprint	blocked; verify and use explicit install
remote version is older	blocked; no automatic downgrade
version order cannot be determined	blocked; no automatic update

--force only permits overwriting local edits during an otherwise valid update. It does not bypass any remote integrity/version guard. Blocked pull/check results use validation exit code 6.

Validation

• cd cli && bun test: 432 passed, 0 failed
• cd cli && bun run typecheck: passed
• cd cli && bun run lint: passed
• cd cli && bun run build: passed
• cd cli && node dist/index.js version: passed
• GitHub CLI matrix: Ubuntu, macOS, Windows passed
• DCO and CLA passed
• independent exact-diff review: no unresolved findings
• exact-SHA release Compose smoke passed at 362ca1e06a76512d61aa9b8aa5b8d98cccb00796, with MinIO pinned to RELEASE.2025-09-07T16-13-09Z and its digest

Manual retest

1. Install integrity:
   cd cli && bun test test/unit/services/install-service.test.ts --test-name-pattern "rejects a downloaded fingerprint mismatch"
   Expected: exit code 6; existing skill directory and inventory remain byte-for-byte unchanged; temporary install directory is removed.
2. Sync decision table:
   cd cli && bun test test/integration/sync-command.test.ts
   Expected: the five rows above are observed; blocked --check and --force exit 6; no install action runs; local files remain unchanged.
3. Force bypass regression:
   In the sync integration output, verify the parameterized local-edit cases cover downgrade, same-version drift, and unknown version order. Each must report blocked, retain changedFiles: ["SKILL.md"], and return no actions.

The running Compose preview validates the exact-SHA server/runtime and MinIO upload/download path. The CLI branch decisions are intentionally reproduced against the controlled fake registry so version and fingerprint combinations can be set deterministically.