feat: 实现跨 API 格式自动转换功能

- 新增端点级 format_acceptance_config 配置，控制是否接受跨格式请求
- 重构 EndpointFormDialog 为卡片式布局，支持内联编辑和格式转换开关
- StreamProcessor 实现流式响应的跨格式转换，支持 OpenAI/Claude/Gemini 互转
- CacheAwareScheduler 按端点格式筛选候选，同格式优先于跨格式
- 健康度/熔断按 Provider 端点格式分桶，而非客户端请求格式
- 新增 format_conversion_total 和 format_conversion_duration_seconds 指标
- 新增全局配置 format_conversion_enabled 控制总开关
- Input 组件新增 size="sm" 尺寸选项

alembic/versions/20260121_1845_4b4c7b0df1a2_add_format_acceptance_config_to_provider_endpoints.py

@@ -0,0 +1,51 @@
+"""add_format_acceptance_config_to_provider_endpoints
+
+Revision ID: 4b4c7b0df1a2
+Revises: c868729753ad
+Create Date: 2026-01-21 18:45:00+00:00
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy import inspect
+
+
+# revision identifiers, used by Alembic.
+revision = "4b4c7b0df1a2"
+down_revision = "c868729753ad"
+branch_labels = None
+depends_on = None
+
+
+def table_exists(table_name: str) -> bool:
+    bind = op.get_bind()
+    inspector = inspect(bind)
+    return table_name in inspector.get_table_names()
+
+
+def column_exists(table_name: str, column_name: str) -> bool:
+    bind = op.get_bind()
+    inspector = inspect(bind)
+    columns = [col["name"] for col in inspector.get_columns(table_name)]
+    return column_name in columns
+
+
+def upgrade() -> None:
+    if not table_exists("provider_endpoints"):
+        return
+    if column_exists("provider_endpoints", "format_acceptance_config"):
+        return
+    op.add_column(
+        "provider_endpoints",
+        sa.Column("format_acceptance_config", sa.JSON(), nullable=True),
+    )
+
+
+def downgrade() -> None:
+    if not table_exists("provider_endpoints"):
+        return
+    if not column_exists("provider_endpoints", "format_acceptance_config"):
+        return
+    op.drop_column("provider_endpoints", "format_acceptance_config")
+