refactor: reorganize project structure and update configurations

- Move migrations/ to database/schema/ for clarity on database schema definitions
- Move sqlc.yaml to internal/database/ to group with database code
- Move static/ to cmd/server/static/ to co-locate with server
- Update all configuration files and documentation
- Follow Go project conventions for better organization

bruno/scanner/Scan Ebooks.bru

@@ -10,15 +10,6 @@ post {
   auth: inherit
 }
 
-body {
-  {
-    "folder_paths": [
-      "/path/to/ebooks",
-      "/another/path/to/ebooks"
-    ]
-  }
-}
-
 settings {
   encodeUrl: true
   timeout: 0
@@ -26,23 +17,27 @@ settings {
 
 docs {
   ## Scan Ebooks
-
-  Manually scans the specified folders for ebooks and adds them to the database.
-
+  
+  Scans the user's configured ebook folders for ebooks and adds them to the database.
+  
   **Method:** POST
-
+  
   **Endpoint:** /api/scanner/scan
-
+  
   **Authentication:** Required
-
+  
   **Request Body:**
-  - `folder_paths` (array of strings, required): Array of folder paths to scan
-
+  - `folder_paths` (array of strings, optional): Array of folder paths to scan. If not provided, uses user's saved folders from Add Ebook Folder.
+  
   **Response:**
   - `message` (string): Success message
-
+  
   **Status Codes:**
   - 200: Success
   - 400: Bad Request
   - 401: Unauthorized
-}
+  
+  **Usage:**
+  - Without body: Scans all folders added via "Add Ebook Folder"
+  - With folder_paths: Scans the specified paths directly (useful for testing)
+}