feat: aether-proxy 远程配置下发、连通性测试与 setup TUI

- 后端新增远程配置管理 API (PUT /config) 和连通性测试 API (POST /test)
- 前端新增远程配置编辑对话框和节点连通性测试按钮
- aether-proxy 支持通过心跳接收并热加载远程配置 (端口白名单、日志级别、心跳间隔、时间戳容差)
- aether-proxy 新增 TOML 配置文件支持和交互式 setup TUI
- aether-proxy 心跳 404 时自动重注册节点
- plain proxy 响应改为流式传输，减少内存缓冲
- 新增 remote_config 和 config_version 数据库字段及迁移

alembic/versions/20260207_1500_3aff3ffc4a0e_add_proxy_node_remote_config.py

@@ -0,0 +1,61 @@
+"""Add remote_config and config_version to proxy_nodes
+
+Revision ID: 3aff3ffc4a0e
+Revises: e1b2c3d4f5a6
+Create Date: 2026-02-07 15:00:00.000000
+
+"""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from sqlalchemy import inspect
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "3aff3ffc4a0e"
+down_revision: str | None = "e1b2c3d4f5a6"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def column_exists(table_name: str, column_name: str) -> bool:
+    bind = op.get_bind()
+    inspector = inspect(bind)
+    columns = [c["name"] for c in inspector.get_columns(table_name)]
+    return column_name in columns
+
+
+def upgrade() -> None:
+    if not column_exists("proxy_nodes", "remote_config"):
+        op.add_column(
+            "proxy_nodes",
+            sa.Column(
+                "remote_config",
+                sa.JSON(),
+                nullable=True,
+                comment="管理端下发的远程配置 (allowed_ports, log_level, heartbeat_interval, timestamp_tolerance)",
+            ),
+        )
+
+    if not column_exists("proxy_nodes", "config_version"):
+        op.add_column(
+            "proxy_nodes",
+            sa.Column(
+                "config_version",
+                sa.Integer(),
+                nullable=False,
+                server_default="0",
+                comment="远程配置版本号，每次更新 +1",
+            ),
+        )
+
+
+def downgrade() -> None:
+    if column_exists("proxy_nodes", "config_version"):
+        op.drop_column("proxy_nodes", "config_version")
+    if column_exists("proxy_nodes", "remote_config"):
+        op.drop_column("proxy_nodes", "remote_config")