feat: add collections management and study coach features

- Implemented collection repository with CRUD operations for user collections.
- Created routes for managing collections, including listing, creating, updating, and deleting collections.
- Added sharing functionality for exams, allowing users to share and clone exams.
- Developed a study coach service that analyzes exam results and provides study tips based on weak areas.
- Introduced frontend components for managing collections, sharing exams, and displaying study coach insights.
- Enhanced user experience with loading states and error handling in shared components.

frontend/src/i18n/en.json

@@ -154,6 +154,7 @@
   },
   "workspace": {
     "myWorkspace": "My Workspace",
+    "overview": "Overview",
     "myExams": "My Exams",
     "results": "Results",
     "settings": "Settings",
@@ -162,6 +163,30 @@
     "noSavedExamsDesc": "Upload an exam from the home page, or create a new one to get started.",
     "createFirstExam": "Create Your First Exam",
     "takeExam": "Take exam",
+    "totalAttempts": "Total Attempts",
+    "avgScore": "Avg. Score",
+    "questionsAnswered": "Questions Answered",
+    "uploadExam": "Upload Exam",
+    "uploadDropzone": "Drop JSON or click to browse",
+    "studyCoachTitle": "Study Coach",
+    "streakDay": "day streak",
+    "streakDays": "day streak",
+    "studyTips": "Study Tips",
+    "retakeWeakest": "Retake Weakest Exam",
+    "performanceTrends": "Performance Trends",
+    "sharedWithMe": "Shared with Me",
+    "noSharedExams": "No shared exams yet",
+    "noSharedExamsDesc": "Exams shared by others will appear here when you save them to your workspace.",
+    "shareMode": "Share mode",
+    "shareModeClone": "Cloneable",
+    "shareModeView": "View only",
+    "importFromUrl": "Import from URL",
+    "importUrlPlaceholder": "Paste a raw JSON URL…",
+    "import": "Import",
+    "importing": "Importing…",
+    "viewAllResults": "View all results",
+    "recentResults": "Recent Results",
+    "viewAll": "View all",
     "noAttempts": "No attempts yet",
     "noAttemptsDesc": "Take an exam to see your results here.",
     "attempts": "attempt",
@@ -211,7 +236,27 @@
     "deleteExamConfirm": "Delete this exam? This cannot be undone.",
     "deleteResultConfirm": "Delete this result? This cannot be undone.",
     "storageWarningHigh": "You are using over 80% of your storage.",
-    "storageWarningCritical": "You are using over 95% of your storage. Delete some items to free up space."
+    "storageWarningCritical": "You are using over 95% of your storage. Delete some items to free up space.",
+    "searchExams": "Search exams…",
+    "noSearchResults": "No exams match your search",
+    "noSearchResultsDesc": "Try a different keyword or clear the search.",
+    "pin": "Pin to top",
+    "unpin": "Unpin",
+    "duplicate": "Duplicate",
+    "export": "Export JSON",
+    "collections": "Collections",
+    "newCollection": "New Collection",
+    "allExams": "All Exams",
+    "uncategorized": "Uncategorized",
+    "moveTo": "Move to",
+    "removeFromCollection": "Remove from collection",
+    "collectionNamePlaceholder": "Collection name…",
+    "create": "Create",
+    "rename": "Rename",
+    "deleteCollectionConfirm": "Delete this collection? Exams will be moved to uncategorized.",
+    "batchSelectAll": "Select all",
+    "batchSelected": "{{count}} selected",
+    "batchDeleteConfirm": "Delete selected exams? This cannot be undone."
   },
   "admin": {
     "aiGrading": {
@@ -346,6 +391,9 @@
     "correctOrder": "Correct Order",
     "correctOrderHint": "The correct order is the order shown above. Reorder items to set the correct sequence.",
     "setCurrentOrder": "Set Current Order as Correct",
+    "tagsLabel": "Tags",
+    "tagsPlaceholder": "Add tag…",
+    "addTag": "Add",
     "examTitleRequired": "Exam title is required",
     "atLeastOneQuestion": "Add at least one question",
     "sourceLanguage": "Source Language",
@@ -398,6 +446,15 @@
     "backToHome": "Back to Home",
     "noToken": "No verification token found."
   },
+  "share": {
+    "share": "Share",
+    "shared": "Shared",
+    "generateLink": "Generate share link",
+    "copyLink": "Copy link",
+    "revokeLink": "Revoke link",
+    "takeExam": "Take this exam",
+    "saveToWorkspace": "Save to my workspace"
+  },
   "resetPassword": {
     "resetPassword": "Reset Password",
     "enterEmail": "Enter your email address and we'll send you a link to reset your password.",