ci: harden check-frontend-only with git diff fallback

- 加 pull-requests: read 权限，避免 github.token 调 /pulls/files 403
- check-frontend-only 优先用 git diff 判断 PR 改动范围，API 失败时自动 fallback
- 修复 #48555 Check if frontend-only change 失败导致 unit-tests 跑全量 diff-cover 被误拦

Closes: CI 纯前端 PR 误跑 Python 测试被覆盖率门槛拦截问题

.gitea/workflows/ci-pipeline.yml

@@ -20,6 +20,7 @@ on:
         default: "手动触发 - CI漏触发补跑"
 permissions:
   contents: read
+  pull-requests: read
 concurrency:
   group: ci-pipeline-${{ gitea.ref }}
   cancel-in-progress: true
@@ -88,9 +89,22 @@ jobs:
         GITHUB_TOKEN: ${{ github.token }}
       run: |
         set -eu
+        # 优先用 git diff 判断 PR 改动范围（比 API 稳定）
         PR_NUMBER=$(echo "$GITHUB_REF" | sed 's|refs/pull/||; s|/.*||')
-        API_URL="${GITHUB_API_URL}/repos/${GITHUB_REPOSITORY}/pulls/${PR_NUMBER}/files?limit=300"
-        FILES=$(curl -s -H "Authorization: token ${GITHUB_TOKEN}" "$API_URL" | python3 -c "import sys,json; [print(f['filename']) for f in json.load(sys.stdin)]")
+        if command -v git >/dev/null 2>&1 && [ -d .git ]; then
+          FILES=$(git diff --name-only origin/develop...HEAD 2>/dev/null || true)
+        fi
+        if [ -z "${FILES:-}" ]; then
+          # fallback 到 API
+          API_URL="${GITHUB_API_URL}/repos/${GITHUB_REPOSITORY}/pulls/${PR_NUMBER}/files?limit=300"
+          FILES=$(curl -sf -H "Authorization: token ${GITHUB_TOKEN}" "$API_URL" | python3 -c "import sys,json; [print(f['filename']) for f in json.load(sys.stdin)]" 2>/dev/null || true)
+        fi
+        if [ -z "${FILES:-}" ]; then
+          echo "⚠️ 无法获取变更文件列表，保守运行完整 CI"
+          echo "skip_backend=false" >> $GITHUB_OUTPUT
+          echo "skip_frontend=false" >> $GITHUB_OUTPUT
+          exit 0
+        fi
         FRONTEND_COUNT=$(echo "$FILES" | grep -c '^apps/web/' || true)
         BACKEND_COUNT=$(echo "$FILES" | grep -cv '^apps/web/' || true)
         TOTAL=$(echo "$FILES" | grep -cv '^$' || true)

apps/web/src/pages/generate/GeneratePage.tsx

@@ -548,10 +548,21 @@ const GeneratePage: React.FC = () => {
             <div
               style={{
                 display: "flex",
-                justifyContent: "center",
+                flexDirection: "column",
+                alignItems: "center",
                 marginTop: 16,
               }}
             >
+              <h2
+                style={{
+                  textAlign: "center",
+                  marginBottom: 12,
+                  fontSize: "1.5rem",
+                  fontWeight: 600,
+                }}
+              >
+                🎬 确认生成
+              </h2>
               <div
                 style={{
                   display: "flex",