fix: delete agent 500 error + dynamic personality + deployment guide

- Fix delete agent 500: clean up FK records (agent_llm_logs, permissions,
  schedules, executions, team_members) and unbind goals/tasks before delete
- Remove hardcoded personality templates in Android, replace with dynamic
  system prompt generation from name + description
- Set promptSectionsEnabled=false to bypass PromptComposer for personality
- Add Tencent Cloud Linux deployment guide (Docker Compose)
- Accumulated backend service updates, frontend UI fixes, Android app changes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/models/push_subscription.py

@@ -0,0 +1,18 @@
+"""浏览器推送订阅模型"""
+from sqlalchemy import Column, String, Text, DateTime, func, JSON
+from sqlalchemy.dialects.mysql import CHAR
+from app.core.database import Base
+import uuid
+
+
+class PushSubscription(Base):
+    __tablename__ = "push_subscriptions"
+
+    id = Column(CHAR(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    user_id = Column(CHAR(36), nullable=True, index=True, comment="关联用户ID")
+    endpoint = Column(Text, nullable=False, comment="推送端点URL")
+    p256dh = Column(Text, nullable=False, comment="公钥")
+    auth = Column(Text, nullable=False, comment="认证密钥")
+    user_agent = Column(String(500), nullable=True, comment="设备UA")
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())