docs(#125): update CLI example to use --vcs-url instead of deprecated --gitea-url

- Add --vcs-url flag as primary (reads VCS_URL env var)
- Keep --gitea-url and GITEA_URL as deprecated fallbacks with warnings
- Update action.yml: rename gitea-url input to vcs-url, pass VCS_URL to binary
- Update ci.yml: use VCS_URL env var in Run review step
- Update integration tests: INTEGRATION_GITEA_URL -> INTEGRATION_VCS_URL
- Update README: --vcs-url / VCS_URL with fallback note in env var table

Backward compat: existing GITEA_URL users get a deprecation warning and
continue to work unchanged until they migrate to VCS_URL.

.gitea/actions/review/action.yml

@@ -124,14 +124,38 @@ runs:
         else
           VERSION="${{ inputs.version }}"
         fi
+
+        # Detect OS and architecture for platform-specific binary download
+        OS_RAW=$(uname -s | tr '[:upper:]' '[:lower:]')
+        case "$OS_RAW" in
+          linux)  OS="linux" ;;
+          darwin) OS="darwin" ;;
+          *)
+            echo "Error: unsupported OS: $(uname -s)" >&2
+            exit 1
+            ;;
+        esac
+
+        RAW_ARCH=$(uname -m)
+        case "$RAW_ARCH" in
+          x86_64)           ARCH="amd64" ;;
+          aarch64 | arm64)  ARCH="arm64" ;;
+          *)
+            echo "Error: unsupported architecture: $RAW_ARCH" >&2
+            exit 1
+            ;;
+        esac
+
         echo "version=${VERSION}" >> "$GITHUB_OUTPUT"
+        echo "os=${OS}" >> "$GITHUB_OUTPUT"
+        echo "arch=${ARCH}" >> "$GITHUB_OUTPUT"
 
     - name: Cache review-bot binary
       id: cache
       uses: actions/cache@v4
       with:
         path: ${{ runner.temp }}/review-bot
-        key: review-bot-linux-amd64-${{ steps.version.outputs.version }}
+        key: review-bot-${{ steps.version.outputs.os }}-${{ steps.version.outputs.arch }}-${{ steps.version.outputs.version }}
 
     - name: Install review-bot
       if: steps.cache.outputs.cache-hit != 'true'
@@ -140,7 +164,7 @@ runs:
         BASE_URL="${{ inputs.vcs-url || github.server_url }}"
         REPO="${{ inputs.repo || 'rodin/review-bot' }}"
         VERSION="${{ steps.version.outputs.version }}"
-        BINARY="review-bot-linux-amd64"
+        BINARY="review-bot-${{ steps.version.outputs.os }}-${{ steps.version.outputs.arch }}"
 
         curl -sSfL "${BASE_URL}/${REPO}/releases/download/${VERSION}/${BINARY}" \
           -o "${{ runner.temp }}/review-bot"
@@ -149,8 +173,13 @@ runs:
 
         # Verify SHA-256 checksum
         cd "${{ runner.temp }}"
-        EXPECTED=$(grep "${BINARY}" checksums.txt | awk '{print $1}')
-        ACTUAL=$(sha256sum review-bot | awk '{print $1}')
+        EXPECTED=$(grep -E "^[[:xdigit:]]+[[:space:]]+\*?${BINARY}$" checksums.txt | awk '{print $1}')
+        # sha256sum (GNU) is not available on macOS; use shasum -a 256 on darwin.
+        if [ "${{ steps.version.outputs.os }}" = "darwin" ]; then
+          ACTUAL=$(shasum -a 256 review-bot | awk '{print $1}')
+        else
+          ACTUAL=$(sha256sum review-bot | awk '{print $1}')
+        fi
 
         if [ -z "$EXPECTED" ]; then
           echo "Error: no checksum found for ${BINARY}" >&2
@@ -164,7 +193,7 @@ runs:
         fi
 
         chmod +x "${{ runner.temp }}/review-bot"
-        echo "Installed review-bot ${VERSION} (checksum verified)"
+        echo "Installed review-bot-${{ steps.version.outputs.os }}-${{ steps.version.outputs.arch }} ${VERSION} (checksum verified)"
 
     - name: Run review
       shell: bash

README.md

@@ -282,7 +282,7 @@ Rules:
 
 ```bash
 review-bot \
-  --gitea-url https://gitea.example.com \
+  --vcs-url https://gitea.example.com \
   --repo owner/name \
   --pr 42 \
   --reviewer-token "$GITEA_TOKEN" \