refactor: move modules under app/ directory and update file paths (#3938)

# Description of Changes

- **What was changed:**  
- Renamed top-level directories: `stirling-pdf` → `app/core`, `common` →
`app/common`, `proprietary` → `app/proprietary`.
- Updated all path references in `.gitattributes`, GitHub workflows
(`.github/workflows/*`), scripts (`.github/scripts/*`), `.gitignore`,
Dockerfiles, license files, and template settings to reflect the new
structure.
- Added a new CI job `check-generateOpenApiDocs` to generate and upload
OpenAPI documentation.
- Removed redundant `@Autowired` annotations from `TempFileShutdownHook`
and `UnlockPDFFormsController`.
- Minor formatting and comment adjustments in YAML templates and
resource files.

- **Why the change was made:**  
- To introduce a clear `app/` directory hierarchy for core, common, and
proprietary modules, improving organization and maintainability.
- To ensure continuous integration and Docker builds continue to work
seamlessly with the reorganized structure.
- To automate OpenAPI documentation generation as part of the CI
pipeline.

---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

.vscode/settings.json

@@ -3,6 +3,9 @@
   "editor.guides.bracketPairs": "active",
   "editor.guides.bracketPairsHorizontal": "active",
   "cSpell.enabled": false,
+  "[feature]": {
+    "editor.defaultFormatter": "alexkrechik.cucumberautocomplete"
+  },
   "[java]": {
     "editor.defaultFormatter": "josevseb.google-java-format-for-vs-code"
   },
@@ -76,13 +79,17 @@
     ".venv*/",
     ".vscode/",
     "bin/",
-    "common/bin/",
-    "proprietary/bin/",
+    "app/core/bin/",
+    "app/common/bin/",
+    "app/proprietary/bin/",
     "build/",
-    "common/build/",
-    "proprietary/build/",
+    "app/core/build/",
+    "app/common/build/",
+    "app/proprietary/build/",
     "configs/",
+    "app/core/configs/",
     "customFiles/",
+    "app/core/customFiles/",
     "docs/",
     "exampleYmlFiles",
     "gradle/",
@@ -94,8 +101,9 @@
     ".git-blame-ignore-revs",
     ".gitattributes",
     ".gitignore",
-    "common/.gitignore",
-    "proprietary/.gitignore",
+    "app/core/.gitignore",
+    "app/common/.gitignore",
+    "app/proprietary/.gitignore",
     ".pre-commit-config.yaml",
   ],
   // Enables signature help in Java.
@@ -127,8 +135,8 @@
   "html.format.maxPreserveNewLines": 2,
   "stylelint.configFile": "devTools/.stylelintrc.json",
   "java.project.sourcePaths": [
-    "stirling-pdf/src/main/java",
-    "common/src/main/java",
-    "proprietary/src/main/java"
+    "app/core/src/main/java",
+    "app/common/src/main/java",
+    "app/proprietary/src/main/java"
   ]
 }