Restructure/frontend editor (#6404)

## Move editor under `frontend/editor/`

Pure restructure: `frontend/` becomes the workspace, `frontend/editor/`
holds
  the PDF editor. 1775 file renames + 40 wiring edits. No logic changes.

  ### Why

`frontend/` is currently the editor — its `src/`, `public/`,
`src-tauri/`,
  config files all sit at the root. Promoting `frontend/` to a
workspace and putting the editor in a sibling folder leaves room for
future
apps to drop in alongside it, sharing one `package.json` /
`node_modules` /
  lint config / Storybook.

  ### What moves

  frontend/
  ├── editor/                ← NEW: everything editor-specific
  │   ├── src/               ← was frontend/src/
  │   ├── public/            ← was frontend/public/
  │   ├── src-tauri/         ← was frontend/src-tauri/
│ ├── index.html, vite.config.ts, vitest.config.ts, playwright.config.ts
  │   ├── tsconfig*.json, tailwind.config.js, postcss.config.js
  │   ├── scripts/
  │   ├── .env, .env.desktop, .env.saas
  │   └── DeveloperGuide.md
├── package.json, package-lock.json, node_modules/ ← workspace install
  ├── eslint.config.mjs, .prettierrc, .prettierignore ← shared tooling
  ├── .gitignore
  └── README.md

  ### Wiring edits (40 files)

  - `.taskfiles/frontend.yml`, `desktop.yml`, `e2e.yml`
  - `build.gradle`, `app/core/build.gradle`
- `eslint.config.mjs`, `frontend/package.json`, `.gitignore`,
`.prettierignore`
  - `docker/frontend/Dockerfile`
  - 8 `.github/workflows/*.yml`, plus `.github/dependabot.yml`,
    `.github/config/.files.yaml`, `.github/labeler-config-srvaroa.yml`
  - `scripts/translations/**`
- Docs: `AGENTS.md`, `CLAUDE.md`, `ADDING_TOOLS.md`,
`DeveloperGuide.md`,
`WINDOWS_SIGNING.md`, `devGuide/HowToAddNewLanguage.md`,
`frontend/README.md`,
    `frontend/editor/DeveloperGuide.md`

Plus 3 renamed + edited: `editor/vite.config.ts` (env path +
node_modules
  walk-up), `editor/scripts/setup-env.mts` (renamed from `.ts` for
`import.meta.url`), `editor/scripts/build-provisioner.mjs` (resolve
src-tauri
  relative to script).

  ### Verification

  | Check | Result |
  |---|---|
  | `task frontend:typecheck:all` (6 variants) | exit 0 |
  | `task frontend:lint` (eslint + dpdm) | exit 0 |
  | `task frontend:format:check` | exit 0 |
  | `task frontend:test` | 657 tests pass, 50 files |
| `task frontend:build:{core,proprietary,saas,desktop,prototypes}` | all
green |
| `task desktop:build` | full Tauri pipeline →
`Stirling-PDF_2.11.0_x64_en-US.msi` |
  | `playwright test --list --project=stubbed` | 172 tests discovered |

`task desktop:build` exercises the heaviest path — Rust + WiX + MSI
bundle
against the moved `editor/src-tauri/`. If anything in the restructure
was
  wrong it wouldn't have built.

  ### Test plan

  - [ ] `frontend-validation.yml` green
  - [ ] `e2e-stubbed.yml` green
  - [ ] `tauri-build.yml` green on at least one platform
  - [ ] `check_toml.yml` runs on a translation-touching PR

---------

Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>

AGENTS.md

@@ -139,9 +139,9 @@ The project structure is defined in `engine/pyproject.toml`. Any new dependencie
 
 #### Environment Variables
 - All `VITE_*` variables must be declared in the appropriate committed env file:
-  - `frontend/.env` — core, proprietary, and shared vars
-  - `frontend/.env.saas` — SaaS-only vars (layered on top of `.env` in SaaS mode)
-  - `frontend/.env.desktop` — desktop (Tauri)-only vars (layered on top of `.env` in desktop mode)
+  - `frontend/editor/.env` — core, proprietary, and shared vars
+  - `frontend/editor/.env.saas` — SaaS-only vars (layered on top of `.env` in SaaS mode)
+  - `frontend/editor/.env.desktop` — desktop (Tauri)-only vars (layered on top of `.env` in desktop mode)
 - These files are committed to Git and must not contain private keys
 - Local overrides (API keys, machine-specific settings) go in uncommitted sibling `.env.local` / `.env.saas.local` / `.env.desktop.local` files — Vite automatically layers them on top
 - Never use `|| 'hardcoded-fallback'` inline — put defaults in the committed env files
@@ -152,7 +152,7 @@ The project structure is defined in `engine/pyproject.toml`. Any new dependencie
 #### Import Paths - CRITICAL
 **ALWAYS use `@app/*` for imports.** Do not use `@core/*` or `@proprietary/*` unless explicitly wrapping/extending a lower layer implementation.
 
-For a broader explanation of the frontend layering and override architecture, see [frontend/DeveloperGuide.md](frontend/DeveloperGuide.md).
+For a broader explanation of the frontend layering and override architecture, see [frontend/editor/DeveloperGuide.md](frontend/editor/DeveloperGuide.md).
 
 ```typescript
 // ✅ CORRECT - Use @app/* for all imports
@@ -243,7 +243,7 @@ Frontend designed for **stateful document processing**:
 - No file reloading between tools - performance critical for large PDFs (up to 100GB+)
 
 #### FileContext - Central State Management
-**Location**: `frontend/src/core/contexts/FileContext.tsx`
+**Location**: `frontend/editor/src/core/contexts/FileContext.tsx`
 - **Active files**: Currently loaded PDFs and their variants
 - **Tool navigation**: Current mode (viewer/pageEditor/fileEditor/toolName)
 - **Memory management**: PDF document cleanup, blob URL lifecycle, Web Worker management
@@ -268,7 +268,7 @@ Without cleanup: browser crashes with memory leaks.
 
 **Architecture**: Modular hook-based system with clear separation of concerns:
 
-- **useToolOperation** (`frontend/src/core/hooks/tools/shared/useToolOperation.ts`): Main orchestrator hook
+- **useToolOperation** (`frontend/editor/src/core/hooks/tools/shared/useToolOperation.ts`): Main orchestrator hook
   - Coordinates all tool operations with consistent interface
   - Integrates with FileContext for operation tracking
   - Handles validation, error handling, and UI state management
@@ -356,7 +356,7 @@ return useToolOperation({
 ### Frontend Directory Structure
 The frontend is organized with a clear separation of concerns:
 
-- **`frontend/src/core/`**: Main application code (shared, production-ready components)
+- **`frontend/editor/src/core/`**: Main application code (shared, production-ready components)
   - **`core/components/`**: React components organized by feature
     - `core/components/tools/`: Individual PDF tool implementations
     - `core/components/viewer/`: PDF viewer components
@@ -374,17 +374,17 @@ The frontend is organized with a clear separation of concerns:
   - **`core/data/`**: Static data (tool taxonomy, etc.)
   - **`core/services/`**: Business logic services (PDF processing, storage, etc.)
 
-- **`frontend/src/desktop/`**: Desktop-specific (Tauri) code
-- **`frontend/src/proprietary/`**: Proprietary/licensed features
-- **`frontend/src-tauri/`**: Tauri (Rust) native desktop application code
-- **`frontend/public/`**: Static assets served directly
+- **`frontend/editor/src/desktop/`**: Desktop-specific (Tauri) code
+- **`frontend/editor/src/proprietary/`**: Proprietary/licensed features
+- **`frontend/editor/src-tauri/`**: Tauri (Rust) native desktop application code
+- **`frontend/editor/public/`**: Static assets served directly
   - `public/locales/`: Translation JSON files
 
 ### Component Architecture
-- **Static Assets**: CSS, JS, and resources in `src/main/resources/static/` (legacy) + `frontend/public/` (modern)
+- **Static Assets**: CSS, JS, and resources in `src/main/resources/static/` (legacy) + `frontend/editor/public/` (modern)
 - **Internationalization**:
   - Backend: `messages_*.properties` files
-  - Frontend: JSON files in `frontend/public/locales/` (converted from .properties)
+  - Frontend: JSON files in `frontend/editor/public/locales/` (converted from .properties)
   - Conversion Script: `scripts/convert_properties_to_json.py`
 
 ### Configuration Modes
@@ -409,7 +409,7 @@ The frontend is organized with a clear separation of concerns:
 4. **Code Style**: Spotless enforces Google Java Format automatically (`task backend:format`)
 5. **Translations**:
    - Backend: Use helper scripts in `/scripts` for multi-language updates
-   - Frontend: Update JSON files in `frontend/public/locales/` or use conversion script
+   - Frontend: Update JSON files in `frontend/editor/public/locales/` or use conversion script
 6. **Documentation**: API docs auto-generated and available at `/swagger-ui/index.html`
 
 ## Frontend Architecture Status
@@ -427,7 +427,7 @@ The frontend is organized with a clear separation of concerns:
 ## Translation Rules
 
 - **CRITICAL**: Always update translations in `en-GB` only, never `en-US`
-- Translation files are located in `frontend/public/locales/`
+- Translation files are located in `frontend/editor/public/locales/`
 
 ## Important Notes