ci: simplify DB cache key and skip yarn-install on cache hit (#26344)

* ci: skip yarn-install in setup-db when DB cache exists

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* ci: skip entire setup-db job when DB cache exists

This saves ~35-40s per workflow run by:
1. Adding DB cache lookup to prepare job (lookup-only mode)
2. Skipping the entire setup-db job when cache exists (avoids postgres container startup)
3. Keeping the yarn-install skip in setup-db.yml as a fallback

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* ci: simplify DB cache key and skip yarn-install on cache hit

- Remove commit SHA and PR number from cache key for better reuse
- Cache key now only depends on prisma schema/migrations hash
- Skip yarn-install in setup-db when DB cache exists (saves ~17s)
- Revert changes to pr.yml required job logic

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* ci: move DB cache lookup to prepare step and skip cache-db on hit

- Move cache lookup to pr.yml prepare step for early detection
- Pass db-cache-hit output to setup-db.yml as input
- Skip yarn-install and cache-db action when cache exists
- setup-db job still runs and reports success (no required job changes)

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* ci: skip container initialization when DB cache exists

- Rename setup-db to setup-db-seed (only runs on cache miss)
- Add lightweight setup-db wrapper job that always returns success
- When cache exists: setup-db-seed is skipped, setup-db returns success
- When cache miss: setup-db-seed runs with postgres, setup-db checks result
- This avoids postgres container startup (~17-20s) when cache exists

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* ci: add cache-db-key action for consistent cache key generation

- Create cache-db-key action to generate DB cache key in one place
- Update cache-db action to use cache-db-key for consistency
- Update pr.yml prepare step to use cache-db-key for lookup
- This ensures the lookup key always matches the actual cache key

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* ci: remove runner.os from cache-db-key

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* ci: simplify setup-db by removing wrapper job

- Remove setup-db wrapper job and rename setup-db-seed back to setup-db
- setup-db is now skipped when cache exists (no container startup)
- Update required check to allow skipped for setup-db when cache hit

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* ci: revert to two-job pattern for setup-db

- setup-db-seed: only runs on cache miss (has postgres container)
- setup-db: wrapper that always runs and reports success
- This ensures downstream jobs (Tests, Production builds) are not skipped
- Reverts required check to simple setup-db.result != 'success'

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* ci: single setup-db job with conditional steps on cache hit

- Removed two-job pattern (setup-db-seed + wrapper)
- Single setup-db job calls setup-db.yml reusable workflow
- Pass DB_CACHE_HIT input from prepare job's db-cache-hit output
- Skip yarn-install and cache-db steps when cache hit (~17s savings)
- Container still starts (will optimize in follow-up)

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

.github/actions/cache-db-key/action.yml

@@ -0,0 +1,23 @@
+name: Generate cache-db key
+description: "Generate the cache key for database caching"
+inputs:
+  path:
+    required: false
+    default: "backups/backup.sql"
+    description: "Path to the backup file"
+outputs:
+  key:
+    description: "The generated cache key"
+    value: ${{ steps.generate-key.outputs.key }}
+runs:
+  using: "composite"
+  steps:
+    - name: Generate cache key
+      id: generate-key
+      shell: bash
+      env:
+        CACHE_NAME: cache-db
+        PATH_KEY: ${{ inputs.path }}
+        PRISMA_HASH: ${{ hashFiles('packages/prisma/schema.prisma', 'packages/prisma/migrations/**/**.sql', 'packages/prisma/*.ts') }}
+      run: |
+        echo "key=${CACHE_NAME}-${PATH_KEY}-${PRISMA_HASH}" >> $GITHUB_OUTPUT