feat: complete migration to Deno with automated releases

- Remove old Node.js infrastructure (package.json, tsconfig.json, bin/nupst launcher, setup.sh)
- Update install.sh to download pre-compiled binaries from Gitea releases
- Add Gitea Actions CI/CD workflows:
  - ci.yml: Type checking, linting, and build verification
  - release.yml: Automated binary compilation and release on tags
- Update .gitignore for Deno-focused project structure
- Binary-based distribution requires no dependencies or build steps

.gitignore

@@ -1,15 +1,18 @@
-# Build
-dist*/
+# Compiled Deno binaries (built by scripts/compile-all.sh)
+dist/binaries/
 
-# Dependencies
+# Deno cache and lock file
+.deno/
+deno.lock
+
+# Legacy Node.js artifacts (v3.x and earlier - kept for safety)
 node_modules/
-
-# Bundled Node.js binaries
 vendor/
+dist_ts/
+npm-debug.log*
 
 # Logs
 *.log
-npm-debug.log*
 
 # Environment
 .env
@@ -18,8 +21,5 @@ npm-debug.log*
 .DS_Store
 Thumbs.db
 
+# Development
 .nogit/
-
-# Deno
-.deno/
-deno.lock