feat(i18n): fix translation QA issues and add automation (#16756)

## Summary

This PR fixes translation QA issues and adds automation to prevent
future issues.

### Translation Fixes
- Fixed **escaped Unicode sequences** in translations (e.g.,
`\u62db\u5f85` → `招待`)
- Removed **corrupted control characters** from .po files (null bytes,
invalid characters)
- Fixed **missing/incorrect placeholders** in various languages
- Deleted **35 problematic translations** via Crowdin API that had
variable mismatches

### New Scripts (in `packages/twenty-utils/`)
- `fix-crowdin-translations.ts` - Auto-fixes encoding issues and syncs
to Crowdin
- `fix-qa-issues.ts` - Fixes specific QA issues via Crowdin API
- `translation-qa-report.ts` - Generates weekly QA report from Crowdin
API

### New Workflow
- `i18n-qa-report.yaml` - Weekly workflow that creates a PR with
translation QA issues for review

### Other Changes
- Moved GitHub Actions from `.github/workflows/actions/` to
`.github/actions/`
- Fixed `date-utils.ts` to avoid nested `t` macros in plural expressions
(root cause of confusing placeholders)

### QA Status After Fixes
| Category | Count | Status |
|----------|-------|--------|
| variables | 0 ✅ | Fixed |
| tags | 1 | Minor |
| empty | 0 ✅ | Fixed |
| spaces | 127 | Low priority |
| numbers | 246 | Locale-specific |
| special_symbols | 268 | Locale-specific |

.github/actions/save-cache/action.yaml

@@ -0,0 +1,21 @@
+name: Save cache
+inputs:
+  key:
+    required: true
+    description: Primary key to the cache, should be retrieved from `cache-restore` composite action outputs.
+  additional-paths:
+    required: false
+
+runs:
+  using: "composite"
+  steps:
+    - name: Save cache
+      uses: actions/cache/save@v4
+      with:
+        key: ${{ inputs.key }}
+        path: |
+          .cache
+          .nx
+          node_modules/.cache
+          packages/*/node_modules/.cache
+          ${{ inputs.additional-paths }}