Add Quick Look Preview and Thumbnail extensions for .casera files

- Add CaseraQLPreview extension to show custom preview with contractor
  details and import instructions when viewing .casera files
- Add CaseraQLThumbnail extension to display teal icon in Messages
  and Files app instead of generic white box
- Update UTExportedTypeDeclarations to conform to public.content
  for better system file type recognition

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

iosApp/CaseraQLPreview/PreviewProvider.swift

@@ -0,0 +1,57 @@
+//
+//  PreviewProvider.swift
+//  CaseraQLPreview
+//
+//  Created by Trey Tartt on 12/6/25.
+//
+
+import QuickLook
+
+class PreviewProvider: QLPreviewProvider, QLPreviewingController {
+    
+
+    /*
+     Use a QLPreviewProvider to provide data-based previews.
+     
+     To set up your extension as a data-based preview extension:
+
+     - Modify the extension's Info.plist by setting
+       <key>QLIsDataBasedPreview</key>
+       <true/>
+     
+     - Add the supported content types to QLSupportedContentTypes array in the extension's Info.plist.
+
+     - Remove
+       <key>NSExtensionMainStoryboard</key>
+       <string>MainInterface</string>
+     
+       and replace it by setting the NSExtensionPrincipalClass to this class, e.g.
+       <key>NSExtensionPrincipalClass</key>
+       <string>$(PRODUCT_MODULE_NAME).PreviewProvider</string>
+     
+     - Implement providePreview(for:)
+     */
+    
+    func providePreview(for request: QLFilePreviewRequest) async throws -> QLPreviewReply {
+    
+        //You can create a QLPreviewReply in several ways, depending on the format of the data you want to return.
+        //To return Data of a supported content type:
+        
+        let contentType = UTType.plainText // replace with your data type
+        
+        let reply = QLPreviewReply.init(dataOfContentType: contentType, contentSize: CGSize.init(width: 800, height: 800)) { (replyToUpdate : QLPreviewReply) in
+
+            let data = Data("Hello world".utf8)
+            
+            //setting the stringEncoding for text and html data is optional and defaults to String.Encoding.utf8
+            replyToUpdate.stringEncoding = .utf8
+            
+            //initialize your data here
+            
+            return data
+        }
+                
+        return reply
+    }
+
+}