Add Gitea Actions CI/CD workflows

- .gitea/workflows/ci.yml: run tests on every push/PR
- .gitea/workflows/release.yml: build Linux binaries on tag push
  - x86_64 (musl static)
  - aarch64 / RPi 64-bit (musl static)
  - armv7 / RPi 32-bit (musl static)
  - Auto-creates Gitea release with all artifacts
- scripts/build-macos-release.sh: build macOS binary locally and
  upload to an existing Gitea release

Release flow:
  git tag v0.1.0 && git push origin v0.1.0
  # CI builds Linux + RPi, creates release
  # Then on Mac: ./scripts/build-macos-release.sh --upload v0.1.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/build-macos-release.sh

@@ -0,0 +1,75 @@
+#!/usr/bin/env bash
+# Build macOS binaries and optionally upload to a Gitea release.
+# Run this on a macOS host (Intel or Apple Silicon).
+#
+# Usage:
+#   ./scripts/build-macos-release.sh                    # build only
+#   ./scripts/build-macos-release.sh --upload v0.1.0    # build + upload to release tag
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+GITEA_URL="https://git.manko.yoga"
+REPO="manawenuz/btest-rs"
+UPLOAD=""
+TAG=""
+
+while [[ $# -gt 0 ]]; do
+    case $1 in
+        --upload) UPLOAD=1; TAG="$2"; shift 2 ;;
+        *) echo "Usage: $0 [--upload TAG]"; exit 1 ;;
+    esac
+done
+
+echo "=== Building macOS release binary ==="
+cargo build --release
+
+ARCH=$(uname -m)
+case "$ARCH" in
+    x86_64) PLATFORM="darwin-x86_64" ;;
+    arm64)  PLATFORM="darwin-aarch64" ;;
+    *)      PLATFORM="darwin-${ARCH}" ;;
+esac
+
+mkdir -p dist
+TARBALL="dist/btest-${PLATFORM}.tar.gz"
+cd target/release
+tar czf "../../${TARBALL}" btest
+cd ../..
+shasum -a 256 "${TARBALL}" > "${TARBALL}.sha256"
+
+echo "Built: ${TARBALL}"
+ls -lh "${TARBALL}"
+cat "${TARBALL}.sha256"
+
+if [[ -n "$UPLOAD" ]]; then
+    if [[ -z "${GITEA_TOKEN:-}" ]]; then
+        echo ""
+        echo "Set GITEA_TOKEN to upload. Example:"
+        echo "  export GITEA_TOKEN=your_token_here"
+        echo "  $0 --upload ${TAG}"
+        exit 1
+    fi
+
+    echo ""
+    echo "=== Uploading to release ${TAG} ==="
+
+    # Find release ID by tag
+    RELEASE_ID=$(curl -s \
+        -H "Authorization: token ${GITEA_TOKEN}" \
+        "${GITEA_URL}/api/v1/repos/${REPO}/releases/tags/${TAG}" | python3 -c "import sys,json; print(json.load(sys.stdin)['id'])")
+
+    echo "Release ID: ${RELEASE_ID}"
+
+    for file in "${TARBALL}" "${TARBALL}.sha256"; do
+        FILENAME=$(basename "$file")
+        echo "Uploading: ${FILENAME}"
+        curl -s -X POST \
+            -H "Authorization: token ${GITEA_TOKEN}" \
+            -F "attachment=@${file}" \
+            "${GITEA_URL}/api/v1/repos/${REPO}/releases/${RELEASE_ID}/assets?name=${FILENAME}"
+        echo ""
+    done
+
+    echo "Done! macOS binary uploaded to ${TAG}"
+fi