fix: don't fail deploy jobs when diagnostic artifact upload hits quota

The prod deploy just failed at Unit Tests even though all 226 tests
passed - the job died on `Upload coverage report` hitting the GitHub
Actions artifact storage quota. ci.yml already treats artifact uploads
as best-effort for this exact reason (comment: "Artifact upload must
never fail the job (storage quota can be full)"), but deploy-prod.yml
and deploy-test.yml were missing the same continue-on-error on their
diagnostic report/screenshot/coverage uploads.

Leaves the actual deployable build artifact uploads (deploy-package-*)
blocking, since a failed deploy really should stop there.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.github/workflows/deploy-prod.yml

@@ -119,6 +119,7 @@ jobs:
 
       - name: Upload coverage report
         uses: actions/upload-artifact@v7
+        continue-on-error: true
         with:
           name: backend-coverage
           path: backend/coverage
@@ -432,6 +433,8 @@ jobs:
       - name: Upload test report
         uses: actions/upload-artifact@v7
         if: always()
+        # Artifact upload must never fail the job (storage quota can be full)
+        continue-on-error: true
         with:
           name: prod-smoke-test-report
           path: tests/playwright-report
@@ -440,6 +443,8 @@ jobs:
       - name: Upload test screenshots
         uses: actions/upload-artifact@v7
         if: failure()
+        # Artifact upload must never fail the job (storage quota can be full)
+        continue-on-error: true
         with:
           name: prod-test-screenshots
           path: tests/test-results

.github/workflows/deploy-test.yml

@@ -247,6 +247,8 @@ jobs:
       - name: Upload test report
         uses: actions/upload-artifact@v7
         if: always()
+        # Artifact upload must never fail the job (storage quota can be full)
+        continue-on-error: true
         with:
           name: e2e-test-report
           path: tests/playwright-report
@@ -255,6 +257,8 @@ jobs:
       - name: Upload test screenshots
         uses: actions/upload-artifact@v7
         if: failure()
+        # Artifact upload must never fail the job (storage quota can be full)
+        continue-on-error: true
         with:
           name: e2e-test-screenshots
           path: tests/test-results