feat: 分离 Alpha 检查与提交限制，优化检查统计与前端展示

backend/app/platform_checks.py

@@ -0,0 +1,23 @@
+"""Classify platform evidence without discarding unknown checks or inferring eligibility."""
+
+
+def is_submission_limit(check):
+    """Recognize only the confirmed account-limit check; unknown names remain Alpha checks."""
+    return isinstance(check, dict) and check.get("name") == "REGULAR_SUBMISSION"
+
+
+def split_checks(checks):
+    """Return Alpha checks and submission limits, retaining malformed Alpha evidence."""
+    items = checks if isinstance(checks, list) else []
+    return ([c for c in items if not is_submission_limit(c)],
+            [c for c in items if is_submission_limit(c)])
+
+
+def submission_limits(checks):
+    """Summarize the observed limit, never the account's current allowance or reset time."""
+    _, limits = split_checks(checks)
+    status = "blocked" if any(c.get("result") == "FAIL" for c in limits) else (
+        "not_blocked" if limits and all(c.get("result") == "PASS" for c in limits) else "unknown"
+    )
+    return {"status": status, "checks": limits,
+            "meaning": "仅反映缓存观测时的提交限制，不代表当前额度或正式提交资格"}