Fix formatting and pin Actions to SHA

- Fix Prettier formatting in SHIP_GATE.md
- Pin actions/checkout to commit SHA for supply chain security

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mcp-tool-shop

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ jobs:
   validate:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - uses: actions/setup-node@v4
         with: