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/knowledge_base.py

@@ -12,6 +12,7 @@ from datetime import datetime
 
 from sqlalchemy import Column, String, Text, Integer, DateTime, ForeignKey, Index
 from sqlalchemy.dialects.mysql import JSON as MySQLJSON
+from sqlalchemy.dialects.mysql import CHAR
 from sqlalchemy.orm import relationship
 
 from app.core.database import Base
@@ -25,6 +26,7 @@ class KnowledgeBase(Base):
     name = Column(String(200), nullable=False, comment="知识库名称")
     description = Column(Text, nullable=True, comment="描述")
     user_id = Column(String(36), nullable=True, index=True, comment="创建者 ID")
+    workspace_id = Column(CHAR(36), ForeignKey("workspaces.id"), nullable=True, comment="所属工作区ID")
     chunk_size = Column(Integer, default=500, comment="分块大小（字符数）")
     chunk_overlap = Column(Integer, default=50, comment="分块重叠（字符数）")
     doc_count = Column(Integer, default=0, comment="文档数量")