fix(#120): detect VCS host for releases API and derive action-repo

Both composite actions hardcoded:
- Gitea's /api/v1/ releases endpoint path
- 'rodin/review-bot' as the action source repo
- .gitea version used GITEA_URL/GITEA_REPO env vars instead of
  GITHUB_SERVER_URL/GITHUB_REPOSITORY

Fix:
- Add 'action-repo' input (default: empty) to allow explicit override
- Auto-detect VCS host from server_url: URLs containing 'gitea' use
  /api/v1/ (Gitea format), all others use /api/v3/ (GitHub format)
- Set smart default action-repo: 'rodin/review-bot' on Gitea,
  'strat/review-bot' on GitHub
- Pass server-url and action-repo as step outputs to avoid re-computing
- Fix .gitea action's 'Run review' env to use GITHUB_SERVER_URL and
  GITHUB_REPOSITORY (matching .github version and review-bot binary
  env var expectations)
- Add .github/workflows/review.yml for self-testing on github.concur.com

Backward compatible: existing Gitea callers using default inputs continue
to resolve rodin/review-bot via /api/v1/ unchanged.

Closes #120

.github/actions/review/action.yml

@@ -104,6 +104,10 @@ inputs:
     description: 'Path to custom persona JSON file'
     required: false
     default: ''
+  action-repo:
+    description: 'Repository hosting the review-bot binary (owner/name). Defaults to rodin/review-bot on Gitea, or strat/review-bot on GitHub.'
+    required: false
+    default: ''
 
 runs:
   using: 'composite'
@@ -112,10 +116,21 @@ runs:
       id: version
       shell: bash
       run: |
-        GITEA_URL="${{ inputs.gitea-url || github.server_url }}"
-        REPO="${{ inputs.repo || 'rodin/review-bot' }}"
+        SERVER_URL="${{ inputs.gitea-url || github.server_url }}"
+        # Detect VCS type: Gitea uses /api/v1/, GitHub uses /api/v3/
+        if echo "$SERVER_URL" | grep -qi 'gitea'; then
+          API_BASE="${SERVER_URL}/api/v1"
+          DEFAULT_ACTION_REPO="rodin/review-bot"
+        else
+          API_BASE="${SERVER_URL}/api/v3"
+          DEFAULT_ACTION_REPO="strat/review-bot"
+        fi
+        ACTION_REPO="${{ inputs.action-repo || '' }}"
+        if [ -z "$ACTION_REPO" ]; then
+          ACTION_REPO="$DEFAULT_ACTION_REPO"
+        fi
         if [ "${{ inputs.version }}" = "latest" ]; then
-          VERSION=$(curl -sSf "${GITEA_URL}/api/v1/repos/${REPO}/releases?limit=1" \
+          VERSION=$(curl -sSf "${API_BASE}/repos/${ACTION_REPO}/releases?limit=1" \
             | python3 -c "import sys, json; releases = json.load(sys.stdin); print(releases[0]['tag_name'] if releases else '')")
           if [ -z "$VERSION" ]; then
             echo "Failed to determine latest version" >&2
@@ -125,6 +140,8 @@ runs:
           VERSION="${{ inputs.version }}"
         fi
         echo "version=${VERSION}" >> "$GITHUB_OUTPUT"
+        echo "action-repo=${ACTION_REPO}" >> "$GITHUB_OUTPUT"
+        echo "server-url=${SERVER_URL}" >> "$GITHUB_OUTPUT"
 
     - name: Cache review-bot binary
       id: cache
@@ -137,14 +154,14 @@ runs:
       if: steps.cache.outputs.cache-hit != 'true'
       shell: bash
       run: |
-        GITEA_URL="${{ inputs.gitea-url || github.server_url }}"
-        REPO="${{ inputs.repo || 'rodin/review-bot' }}"
+        SERVER_URL="${{ steps.version.outputs.server-url }}"
+        ACTION_REPO="${{ steps.version.outputs.action-repo }}"
         VERSION="${{ steps.version.outputs.version }}"
         BINARY="review-bot-linux-amd64"
 
-        curl -sSfL "${GITEA_URL}/${REPO}/releases/download/${VERSION}/${BINARY}" \
+        curl -sSfL "${SERVER_URL}/${ACTION_REPO}/releases/download/${VERSION}/${BINARY}" \
           -o "${{ runner.temp }}/review-bot"
-        curl -sSfL "${GITEA_URL}/${REPO}/releases/download/${VERSION}/checksums.txt" \
+        curl -sSfL "${SERVER_URL}/${ACTION_REPO}/releases/download/${VERSION}/checksums.txt" \
           -o "${{ runner.temp }}/checksums.txt"
 
         # Verify SHA-256 checksum