ci: add CI checks and tag-triggered release workflow

Phase 2 of the 0.1.0 release prep, running on the GitHub mirror:
- ci.yml: frontend type-check/build, rustfmt gate, clippy (CPU-only) on
  windows-latest with pnpm + rust caching
- release.yml: v* tags build the NSIS installer via tauri-action and attach
  it to a draft GitHub Release with updater JSON; updater signing secrets
  referenced ahead of Phase 3
- both build --no-default-features: runners have no CUDA toolkit, and the
  shipped artifact must be the CPU/DirectML build

.github/workflows/release.yml

@@ -0,0 +1,54 @@
+name: Release
+
+# Tag pushes mirrored from Gitea (git.jezz.wtf) trigger this on the GitHub
+# mirror. Builds the NSIS installer and attaches it to a DRAFT GitHub Release —
+# review and publish manually.
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+
+jobs:
+  release:
+    permissions:
+      contents: write
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 11
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+
+      - name: Install Rust stable
+        uses: dtolnay/rust-toolchain@stable
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: src-tauri
+
+      - name: Install frontend dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Build and create draft release
+        uses: tauri-apps/tauri-action@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          # Updater artifact signing (Phase 3) — set these repo secrets once
+          # the updater keypair exists; empty values are ignored until then.
+          TAURI_SIGNING_PRIVATE_KEY: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY }}
+          TAURI_SIGNING_PRIVATE_KEY_PASSWORD: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY_PASSWORD }}
+        with:
+          tagName: ${{ github.ref_name }}
+          releaseName: 'Phokus v__VERSION__'
+          releaseBody: 'See the assets below to download and install this version.'
+          releaseDraft: true
+          prerelease: false
+          uploadUpdaterJson: true
+          updaterJsonPreferNsis: true