chore: update project structure and workflows

- Update .gitignore for new backend structure
- Update GitHub workflows for transcriptarr rename
- Update launcher.py to use new module name

.github/workflows/build_CPU.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Get version from subgen.py
+      - name: Get version from transcriptarr.py
         id: get_version
         run: |
           version=$(grep -oP "subgen_version\s*=\s*'\K[^']+" subgen.py)