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/dashboard.go

@@ -129,10 +129,10 @@ func (h *DashboardHandler) RestoreSystemCollection(c *echo.Context) error {
 	}
 
 	validCollections := map[string]bool{
-		"continue-reading": true,
-		"recently-added":   true,
-		"recently-read":    true,
-		"not-started":      true,
+		"Continue Reading": true,
+		"Recently Added":   true,
+		"Recently Read":    true,
+		"Not Started":      true,
 	}
 	if !validCollections[req.CollectionName] {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "Invalid system collection name"})