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

.gitea/workflows/ci.yml

@@ -0,0 +1,85 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+      - 'migration/**'
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  check:
+    name: Type Check & Lint
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Deno
+        uses: denoland/setup-deno@v1
+        with:
+          deno-version: v1.x
+
+      - name: Check TypeScript types
+        run: deno check mod.ts
+
+      - name: Lint code
+        run: deno lint
+        continue-on-error: true
+
+      - name: Format check
+        run: deno fmt --check
+        continue-on-error: true
+
+  build:
+    name: Build Test (Current Platform)
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Deno
+        uses: denoland/setup-deno@v1
+        with:
+          deno-version: v1.x
+
+      - name: Compile for current platform
+        run: |
+          echo "Testing compilation for Linux x86_64..."
+          deno compile --allow-all --no-check \
+            --output nupst-test \
+            --target x86_64-unknown-linux-gnu mod.ts
+
+      - name: Test binary execution
+        run: |
+          chmod +x nupst-test
+          ./nupst-test --version
+          ./nupst-test help
+
+  build-all:
+    name: Build All Platforms (Tag/Main only)
+    runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/main' || startsWith(github.ref, 'refs/tags/')
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Deno
+        uses: denoland/setup-deno@v1
+        with:
+          deno-version: v1.x
+
+      - name: Compile all platform binaries
+        run: bash scripts/compile-all.sh
+
+      - name: Upload binaries as artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: nupst-binaries
+          path: dist/binaries/*
+          retention-days: 30