Add PyInstaller spec and Gitea Actions CI for Linux/Windows binaries

- run.py: top-level entry point for PyInstaller (relative imports need it)
- psp-preserve.spec: onedir build bundling DATs, loader, cover bundles, icons
- requirements-build.txt: pinned build deps (PySide6 6.8.3 for Windows ICU fix)
- .gitea/workflows/build.yml: builds linux + windows artifacts on tags/manual
- gitignore build/ dist/

.gitignore

@@ -19,4 +19,8 @@ data/ps1_templates/
 data/nps/*.tsv
 
 # Local environment overrides (LAN paths, secrets). See .env.example
-.env
+.env
+
+# PyInstaller output
+build/
+dist/