feat: aether-proxy TLS 双栈支持与自签名证书自动生成

- aether-proxy 新增 TLS 模块：自签名证书生成、TLS acceptor 构建、证书 SHA-256 指纹计算
- 代理服务器支持 HTTP+TLS 双栈模式，通过 peek 首字节区分 TLS ClientHello 与普通 HTTP
- 注册与心跳上报 tls_enabled 和 tls_cert_fingerprint 字段
- Python 侧 httpx 代理适配：TLS 代理使用 httpx.Proxy + CERT_NONE ssl_context
- ProxyNode 模型新增 tls_enabled/tls_cert_fingerprint 字段及对应迁移

alembic/versions/20260207_1800_4b5c6d7e8f9a_add_tls_to_proxy_nodes.py

@@ -0,0 +1,61 @@
+"""Add tls_enabled and tls_cert_fingerprint to proxy_nodes
+
+Revision ID: 4b5c6d7e8f9a
+Revises: 3aff3ffc4a0e
+Create Date: 2026-02-07 18:00:00.000000
+
+"""
+
+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 = "4b5c6d7e8f9a"
+down_revision: str | None = "3aff3ffc4a0e"
+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", "tls_enabled"):
+        op.add_column(
+            "proxy_nodes",
+            sa.Column(
+                "tls_enabled",
+                sa.Boolean(),
+                nullable=False,
+                server_default="false",
+                comment="是否启用 TLS 加密",
+            ),
+        )
+
+    if not column_exists("proxy_nodes", "tls_cert_fingerprint"):
+        op.add_column(
+            "proxy_nodes",
+            sa.Column(
+                "tls_cert_fingerprint",
+                sa.String(128),
+                nullable=True,
+                comment="TLS 证书 SHA-256 指纹（hex）",
+            ),
+        )
+
+
+def downgrade() -> None:
+    if column_exists("proxy_nodes", "tls_cert_fingerprint"):
+        op.drop_column("proxy_nodes", "tls_cert_fingerprint")
+    if column_exists("proxy_nodes", "tls_enabled"):
+        op.drop_column("proxy_nodes", "tls_enabled")