feat: 核心模块增强 — 加密 + 运行时配置 + 日志缓冲

- crypto.py: API Key 加密/解密工具
- runtime_config.py: 运行时动态配置管理
- log_buffer.py: 内存日志缓冲区
- config.py: 新增加密配置项
- http_client.py: 增强重试和错误处理

alembic/versions/0010_app_settings.py

@@ -0,0 +1,30 @@
+"""新增 app_settings 表(后台运行时配置)
+
+Revision ID: 0010_app_settings
+Revises: 0009_match_stats_xg_fields
+Create Date: 2026-09-18
+
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+revision: str = '0010_app_settings'
+down_revision: Union[str, None] = '0009_match_stats_xg_fields'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        'app_settings',
+        sa.Column('key', sa.String(100), primary_key=True),
+        sa.Column('value', sa.Text(), nullable=False),
+        sa.Column('updated_at', sa.DateTime(timezone=True), server_default=sa.func.now()),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table('app_settings')