Update default system collection names to Title Case format

Changed the 4 default system collection names from kebab-case to Title Case
with spaces for better readability and professional appearance:

Changes:
- "continue-reading" → "Continue Reading"
- "recently-added" → "Recently Added"
- "recently-read" → "Recently Read"
- "not-started" → "Not Started"

Implementation details:
- Collection Name field: Updated to Title Case (user-visible identifier)
- QueryType field: Unchanged, remains kebab-case (internal switch/case logic)
- All map keys updated to use new Title Case names as lookups
- Restore modal option values updated to match new names

Files modified:
- internal/handlers/auth.go: Default collection creation for new users
- internal/handlers/dashboard.go: Restore endpoint validation map
- internal/services/dashboard_service.go: System collection metadata map
- templates/restore_system_collection_modal.templ: Form option values

Benefits:
- Cleaner, more professional display names for end users
- Consistent with existing restore modal UI labels
- Improved user experience with properly formatted collection names
- Internal QueryType identifiers remain unchanged for code logic

internal/handlers/auth.go

@@ -989,10 +989,10 @@ func (h *AuthHandler) CreateDefaultCollectionsForUser(ctx context.Context, userI
 		QueryType   string
 		Priority    int32
 	}{
-		{"continue-reading", "Books you're currently reading (0 < progress < 1)", "📖", "#7aa2f7", "continue-reading", 1},
-		{"recently-added", "Newly added items to this library", "🆕", "#9ece6a", "recently-added", 2},
-		{"recently-read", "Books you've finished (progress >= 1)", "✅", "#e0af68", "recently-read", 3},
-		{"not-started", "Books you haven't read yet (progress = 0 or no record)", "📕", "#f7768e", "not-started", 4},
+		{"Continue Reading", "Books you're currently reading (0 < progress < 1)", "📖", "#7aa2f7", "continue-reading", 1},
+		{"Recently Added", "Newly added items to this library", "🆕", "#9ece6a", "recently-added", 2},
+		{"Recently Read", "Books you've finished (progress >= 1)", "✅", "#e0af68", "recently-read", 3},
+		{"Not Started", "Books you haven't read yet (progress = 0 or no record)", "📕", "#f7768e", "not-started", 4},
 	}
 
 	for _, col := range defaultCollections {