PDF Text editor (#4724)

## Summary
- add a `PdfJsonConversionService` that serializes PDF text, fonts, and
metadata to JSON and rebuilds a PDF from the same structure
- expose REST endpoints for `/pdf/json` and `/json/pdf` conversions
using the existing convert API infrastructure
- define JSON model classes capturing document metadata, font
information, and positioned text elements

## Testing
- `./gradlew spotlessApply` *(fails: plugin
org.springframework.boot:3.5.4 unavailable in build environment)*
- `./gradlew build` *(fails: plugin org.springframework.boot:3.5.4
unavailable in build environment)*

------
https://chatgpt.com/codex/tasks/task_b_68f8e98d94ac8328a0e499e541528b6f

---------

Co-authored-by: EthanHealy01 <[email protected]>

frontend/src/core/constants/convertConstants.ts

@@ -33,7 +33,9 @@ export const CONVERSION_ENDPOINTS = {
   'pdf-pdfa': '/api/v1/convert/pdf/pdfa',
   'html-pdf': '/api/v1/convert/html/pdf',
   'markdown-pdf': '/api/v1/convert/markdown/pdf',
-  'eml-pdf': '/api/v1/convert/eml/pdf'
+  'eml-pdf': '/api/v1/convert/eml/pdf',
+  'pdf-text-editor': '/api/v1/convert/pdf/text-editor',
+  'text-editor-pdf': '/api/v1/convert/text-editor/pdf'
 } as const;
 
 export const ENDPOINT_NAMES = {
@@ -52,7 +54,9 @@ export const ENDPOINT_NAMES = {
   'pdf-pdfa': 'pdf-to-pdfa',
   'html-pdf': 'html-to-pdf',
   'markdown-pdf': 'markdown-to-pdf',
-  'eml-pdf': 'eml-to-pdf'
+  'eml-pdf': 'eml-to-pdf',
+  'pdf-text-editor': 'pdf-to-text-editor',
+  'text-editor-pdf': 'text-editor-to-pdf'
 } as const;
 
 

frontend/src/core/constants/convertSupportedFornats.ts

@@ -5,7 +5,7 @@ export const CONVERT_SUPPORTED_FORMATS = [
   // OpenDocument
   'odt', 'ott', 'ods', 'ots', 'odp', 'otp', 'odg', 'otg',
   // Text formats
-  'txt', 'text', 'xml', 'rtf', 'html', 'lwp', 'md',
+  'txt', 'text', 'xml', 'rtf', 'html', 'lwp', 'md', 'json',
   // Images
   'bmp', 'gif', 'jpeg', 'jpg', 'png', 'tif', 'tiff', 'pbm', 'pgm', 'ppm', 'ras', 'xbm', 'xpm', 'svg', 'svm', 'wmf', 'webp',
   // StarOffice