gha cleanups (#6275)

# Description of Changes

Adds all pre commit PR checks under single file with job validator to
have a true "required" run step "all-checks-passed" check
Moves all GHAs into workflow helper function calls 

Note if: always() overrides the default skip-on-needs-failure, "Needs"
is added to ensure the validation runs at end of all other tasks

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/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)
- [ ] I have performed a self-review of my own code
- [ ] 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)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### 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 run `task check` to verify linters, typechecks, and tests
pass
- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#7-testing)
for more details.

.github/config/.files.yaml

@@ -55,6 +55,25 @@ frontend: &frontend
   - scripts/type3_to_cff.py
   - scripts/update_type3_library.py
 
+# Files that affect the Tauri desktop bundle. Gate the multi-OS Tauri build
+# job on changes to any of these.
+tauri: &tauri
+  - frontend/src-tauri/**
+  - frontend/src/desktop/**
+  - frontend/tsconfig.desktop.json
+  - frontend/package.json
+  - frontend/package-lock.json
+  - frontend/vite.config.ts
+  - .github/workflows/tauri-build.yml
+
+# Files that affect the AI engine (Python tool models, fixers, tests). Gate
+# the engine validation job on changes to engine sources or to the Java
+# tool surfaces it generates models from.
+engine: &engine
+  - engine/**
+  - app/(common|core|proprietary)/src/main/java/**
+  - .github/workflows/ai-engine.yml
+
 licenses-frontend: &licenses-frontend
   - ".github/workflows/frontend-backend-licenses-update.yml"
   - "frontend/package.json"