refactor: simplify translations — shared utils, deduplicated code

- Extract shared constants to client/src/utils/translations.js
  (AVAILABLE_LANGUAGES, TRANSLATION_STATUS_COLORS, isTextSelected, groupTextsByLanguage)
- TranslationDetailPanel: deduplicate copy button JSX, hoist hasSelected
- PublicTranslationReview: memoize textsByLanguage, use shared isTextSelected
- Translations page: import from shared module
- Server: translation schema updates, post_id linking
- Add reassign-user utility script
- Add new translation i18n keys to en.json and ar.json

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/src/i18n/en.json

@@ -922,6 +922,30 @@
   "review.confirmRejectPostDesc": "Are you sure you want to reject this post? Please provide feedback explaining why.",
   "review.feedbackRequired": "Feedback (required)",
   "review.feedbackRequiredError": "Please provide feedback when rejecting",
+  "review.loadFailed": "Failed to load review",
+  "review.errorTitle": "Error",
+  "review.thankYou": "Thank you for your review!",
+  "review.approveSuccess": "Translation approved successfully!",
+  "review.rejectSuccess": "Translation has been rejected.",
+  "review.revisionSuccess": "Revision requested successfully.",
+  "review.nameRequired": "Please provide your name",
+  "review.yourReview": "Your Review",
+  "review.selectYourName": "Select your name",
+  "review.selectApprover": "Select approver...",
+  "review.yourName": "Your Name",
+  "review.enterYourName": "Enter your name...",
+  "review.feedback": "Feedback",
+  "review.feedbackPlaceholder": "Share your thoughts or feedback...",
+  "review.approve": "Approve",
+  "review.approved": "Approved",
+  "review.rejected": "Rejected",
+  "review.requestRevision": "Request Revision",
+  "review.reject": "Reject",
+  "review.statusLabel": "Status",
+  "review.reviewedBy": "Reviewed by",
+  "review.confirmReject": "Confirm Rejection",
+  "review.rejectConfirmDesc": "Are you sure you want to reject this translation? Please make sure you have provided feedback.",
+  "review.feedbackRequiredForReject": "Please provide feedback before rejecting.",
   "posts.versions": "Versions",
   "posts.newVersion": "New Version",
   "posts.createNewVersion": "Create New Version",
@@ -961,7 +985,6 @@
   "translations.status": "Status",
   "translations.languagesLabel": "Languages",
   "translations.languagesCount": "languages",
-  "translations.updated": "Updated",
   "translations.grid": "Grid",
   "translations.list": "List",
   "translations.allBrands": "All Brands",
@@ -991,9 +1014,9 @@
   "translations.draftSaved": "Draft saved!",
   "translations.failedSaveDraft": "Failed to save draft",
   "translations.saveDraft": "Save Draft",
-  "translations.saveDraftTooltip": "Save changes to title, description, and source content",
+  "translations.saveDraftTooltip": "Save changes to title and source content",
   "translations.savingDraft": "Saving...",
-  "translations.updated": "Updated!",
+  "translations.updated": "Updated",
   "translations.failedUpdate": "Failed to update",
   "translations.addTranslation": "Add Translation",
   "translations.translationAdded": "Translation added!",
@@ -1021,5 +1044,26 @@
   "translations.approvedByLabel": "Approved by",
   "translations.pendingReviewInfo": "This translation is currently pending review.",
   "translations.noReviewInfo": "No review information available.",
-  "translations.failedDelete": "Failed to delete"
+  "translations.failedDelete": "Failed to delete",
+  "translations.addOption": "Add Option",
+  "translations.option": "option",
+  "translations.options": "options",
+  "translations.optionLabel": "Option",
+  "translations.selected": "Selected",
+  "translations.selectThis": "Select",
+  "translations.optionSelected": "Option selected!",
+  "translations.suggestAlternative": "Suggest alternative",
+  "translations.suggestForLang": "Suggest a translation for",
+  "translations.enterSuggestion": "Enter your suggested translation...",
+  "translations.submitSuggestion": "Submit Suggestion",
+  "translations.suggestionAdded": "Suggestion added!",
+  "translations.existing": "existing",
+  "translations.copyContent": "Copy to clipboard",
+  "translations.copiedToClipboard": "Copied to clipboard!",
+  "translations.approvedReadOnly": "This translation is approved and cannot be modified.",
+  "translations.linkedPost": "Linked Post",
+  "translations.createPost": "New Post",
+  "translations.newPostTitle": "Post title...",
+  "translations.postCreated": "Post created!",
+  "translations.postCreateFailed": "Failed to create post"
 }