feat: 自适应 RPM 未学习时不限制，改为碰壁学习策略

- 移除自适应模式的默认初始限制（RPMDefaults.INITIAL_LIMIT）
- 未学习到边界前不限制 RPM，让系统自由运行直到遇到 429
- 前端自适应 Key 显示学习到的值或"探测中"状态
- 批量余额查询改为并行执行，提升性能

src/api/admin/adaptive.py

@@ -18,7 +18,6 @@ from sqlalchemy.orm import Session
 
 from src.api.base.admin_adapter import AdminApiAdapter
 from src.api.base.pipeline import ApiRequestPipeline
-from src.config.constants import RPMDefaults
 from src.core.exceptions import InvalidRequestException, translate_pydantic_error
 from src.database import get_db
 from src.models.database import ProviderAPIKey
@@ -226,7 +225,7 @@ class ListAdaptiveKeysAdapter(AdminApiAdapter):
                 is_adaptive=key.rpm_limit is None,
                 rpm_limit=key.rpm_limit,
                 effective_limit=(
-                    (key.learned_rpm_limit if key.learned_rpm_limit is not None else RPMDefaults.INITIAL_LIMIT)
+                    key.learned_rpm_limit  # 自适应模式：使用学习值，未学习时为 None（不限制）
                     if key.rpm_limit is None
                     else key.rpm_limit
                 ),
@@ -279,7 +278,7 @@ class ToggleAdaptiveModeAdapter(AdminApiAdapter):
             "is_adaptive": is_adaptive,
             "rpm_limit": key.rpm_limit,
             "effective_limit": (
-                (key.learned_rpm_limit if key.learned_rpm_limit is not None else RPMDefaults.INITIAL_LIMIT)
+                key.learned_rpm_limit  # 自适应模式：使用学习值，未学习时为 None（不限制）
                 if is_adaptive
                 else key.rpm_limit
             ),

src/api/admin/endpoints/keys.py

@@ -13,7 +13,6 @@ from sqlalchemy.orm import Session
 from src.api.base.admin_adapter import AdminApiAdapter
 from src.api.base.models_service import invalidate_models_list_cache
 from src.api.base.pipeline import ApiRequestPipeline
-from src.config.constants import RPMDefaults
 from src.core.crypto import crypto_service
 from src.core.exceptions import InvalidRequestException, NotFoundException
 from src.core.key_capabilities import get_capability
@@ -539,11 +538,7 @@ def _build_key_response(
             "avg_response_time_ms": round(avg_response_time_ms, 2),
             "is_adaptive": is_adaptive,
             "effective_limit": (
-                (
-                    key.learned_rpm_limit
-                    if key.learned_rpm_limit is not None
-                    else RPMDefaults.INITIAL_LIMIT
-                )
+                key.learned_rpm_limit  # 自适应模式：使用学习值，未学习时为 None（不限制）
                 if is_adaptive
                 else key.rpm_limit
             ),