ci: add nightly binary release workflow (Closes #17)

Cross-platform builds (linux, macOS x86+arm, Windows) published
as rolling nightly GitHub release via softprops/action-gh-release.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: noahgift

.github/workflows/nightly.yml

@@ -0,0 +1,110 @@
+name: Nightly Binary Release
+
+on:
+  schedule:
+    - cron: '0 4 * * *'
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build:
+    name: Build ${{ matrix.target }}
+    runs-on: ${{ matrix.runner }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - target: x86_64-unknown-linux-gnu
+            runner: ubuntu-latest
+            binary: presentar
+            artifact: presentar-x86_64-linux
+            use_cross: true
+          - target: x86_64-apple-darwin
+            runner: macos-latest
+            binary: presentar
+            artifact: presentar-x86_64-macos
+            use_cross: false
+          - target: aarch64-apple-darwin
+            runner: macos-latest
+            binary: presentar
+            artifact: presentar-aarch64-macos
+            use_cross: false
+          - target: x86_64-pc-windows-msvc
+            runner: windows-latest
+            binary: presentar.exe
+            artifact: presentar-x86_64-windows.exe
+            use_cross: false
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: ${{ matrix.target }}
+
+      - name: Install cross
+        if: matrix.use_cross
+        run: cargo install cross --locked
+
+      - name: Build (cross)
+        if: matrix.use_cross
+        run: cross build --release --target ${{ matrix.target }} -p presentar-cli
+
+      - name: Build (native)
+        if: "!matrix.use_cross"
+        run: cargo build --release --target ${{ matrix.target }} -p presentar-cli
+
+      - name: Rename binary
+        shell: bash
+        run: cp target/${{ matrix.target }}/release/${{ matrix.binary }} ${{ matrix.artifact }}
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ matrix.artifact }}
+          path: ${{ matrix.artifact }}
+
+  release:
+    name: Publish Nightly Release
+    needs: build
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Download all artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: artifacts/
+
+      - name: Prepare release assets
+        run: |
+          mkdir -p release/
+          find artifacts/ -type f | while read f; do
+            cp "$f" release/
+          done
+          ls -lh release/
+
+      - name: Delete existing nightly tag
+        run: gh release delete nightly --cleanup-tag -y || true
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Create nightly release
+        uses: softprops/action-gh-release@v2
+        with:
+          tag_name: nightly
+          name: "Nightly Build (${{ github.sha }})"
+          body: |
+            Automated nightly build from `main` branch.
+            Commit: ${{ github.sha }}
+            Date: ${{ github.event.head_commit.timestamp || github.event.repository.updated_at }}
+          prerelease: true
+          files: release/*
+          make_latest: false