Implement complete API routes and mock authentication for full CMS functionality

- Add comprehensive nested route structure with proper authentication layers
- Implement UpdateContent and ReorderCollectionItems handlers with repository pattern
- Add automatic mock JWT token fetching for seamless development workflow
- Restore content editing and collection reordering functionality broken after database refactoring
- Provide production-ready authentication architecture with development convenience
- Enable full CMS operations in browser with proper CRUD and bulk transaction support

internal/api/models.go

@@ -1,5 +1,7 @@
 package api
 
+import "github.com/insertr/insertr/internal/db"
+
 // Use db package types directly for API responses - no duplication needed
 // Request models are kept below as they're different (input DTOs)
 
@@ -59,12 +61,7 @@ type UpdateCollectionItemRequest struct {
 	UpdatedBy   string `json:"updated_by,omitempty"`
 }
 
-type CollectionItemPosition struct {
-	ItemID   string `json:"itemId"`
-	Position int    `json:"position"`
-}
-
 type ReorderCollectionRequest struct {
-	Items     []CollectionItemPosition `json:"items"`
-	UpdatedBy string                   `json:"updated_by,omitempty"`
+	Items     []db.CollectionItemPosition `json:"items"`
+	UpdatedBy string                      `json:"updated_by,omitempty"`
 }