feat: support Grok platform account imports

backend/app/routers/websites.py

@@ -593,14 +593,24 @@ def import_groups_from_upstream(
     )
 
 
-SUPPORTED_PLATFORMS = {"openai", "anthropic", "gemini", "antigravity"}
+def _normalize_platform(platform: str) -> str:
+    """统一平台值：小写、xai → grok。"""
+    p = platform.lower().strip()
+    if p == "xai":
+        return "grok"
+    return p
+
+
+SUPPORTED_PLATFORMS = {"openai", "anthropic", "gemini", "grok", "antigravity"}
 
 
 def _resolve_platform(text: str, group_snapshot: dict | None, fallback: str = "openai") -> str:
     if group_snapshot and isinstance(group_snapshot, dict):
-        platform = group_snapshot.get("platform")
-        if platform and str(platform).lower() in SUPPORTED_PLATFORMS:
-            return str(platform).lower()
+        raw = group_snapshot.get("platform")
+        if raw:
+            platform = _normalize_platform(str(raw))
+            if platform in SUPPORTED_PLATFORMS:
+                return platform
     return _detect_platform(text, fallback)
 
 
@@ -611,9 +621,11 @@ def _detect_platform(text: str, fallback: str = "openai") -> str:
         return "anthropic"
     if "gemini" in lower:
         return "gemini"
+    if "grok" in lower or "xai" in lower:
+        return "grok"
     if "antigravity" in lower:
         return "antigravity"
-    return fallback
+    return _normalize_platform(fallback)
 
 
 @router.post("/api/websites/{wid}/accounts/sync-imported-upstream-keys", response_model=ImportAccountsResponse)
@@ -869,7 +881,7 @@ def import_upstream_keys_as_accounts(
                     body.default_platform,
                 )
             else:
-                platform = body.default_platform
+                platform = _normalize_platform(body.default_platform)
 
             upstream = upstreams_map.get(row.upstream_id)
             upstream_name = upstream.name if upstream else "Unknown"