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/proprietary/data/useProprietaryToolRegistry.tsx

@@ -1,5 +1,13 @@
 import { useMemo } from "react";
-import { type ProprietaryToolRegistry } from "@app/data/toolsTaxonomy";
+import LocalIcon from "@app/components/shared/LocalIcon";
+import { useTranslation } from "react-i18next";
+import { getSynonyms } from "@app/utils/toolSynonyms";
+import PdfTextEditor from "@app/tools/pdfTextEditor/PdfTextEditor";
+import {
+  SubcategoryId,
+  ToolCategoryId,
+  type ProprietaryToolRegistry,
+} from "@app/data/toolsTaxonomy";
 
 /**
  * Hook that provides the proprietary tool registry.
@@ -8,6 +16,26 @@ import { type ProprietaryToolRegistry } from "@app/data/toolsTaxonomy";
  * and will be included in the main tool registry.
  */
 export function useProprietaryToolRegistry(): ProprietaryToolRegistry {
-  return useMemo(() => ({
-  }), []);
+  const { t } = useTranslation();
+
+  return useMemo<ProprietaryToolRegistry>(() => ({
+    pdfTextEditor: {
+      icon: <LocalIcon icon="edit-square-outline-rounded" width="1.5rem" height="1.5rem" />,
+      name: t("home.pdfTextEditor.title", "PDF Text Editor"),
+      component: PdfTextEditor,
+      description: t(
+        "home.pdfTextEditor.desc",
+        "Review and edit text and images in PDFs with grouped text editing and PDF regeneration"
+      ),
+      categoryId: ToolCategoryId.RECOMMENDED_TOOLS,
+      subcategoryId: SubcategoryId.GENERAL,
+      maxFiles: 1,
+      endpoints: ["text-editor-pdf"],
+      synonyms: getSynonyms(t, "pdfTextEditor"),
+      supportsAutomate: false,
+      automationSettings: null,
+      versionStatus: "alpha",
+      requiresPremium: true,
+    },
+  }), [t]);
 }