feat: 修复 H5 底部导航覆盖 + 更新项目进度文档

## H5 底部导航修复 (Bug #10)
- 精简 App.vue，移除重复 tabbar，仅保留全局样式
- uni-page 设置 height: calc(100% - 50px) + overflow-y: auto
- 内容区域精确停在底部导航上方，独立滚动不再叠加
- 恢复 custom-tab-bar 组件

## 项目进度文档
- PROGRESS.md 更新至 10 个 Bug 修复
- 新增 H5 底部导航修复记录
- 新增历史变更条目

backend/app/models/customer.py

@@ -10,7 +10,7 @@ class Customer(Base):
     __tablename__ = "customers"
 
     id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
-    user_id = Column(UUID(as_uuid=True), nullable=False, index=True)
+    user_id = Column(UUID(as_uuid=True), ForeignKey("users.id"), nullable=False, index=True)
     name = Column(String(255), nullable=False)
     company = Column(String(255))
     country = Column(String(100))
@@ -38,7 +38,7 @@ class Conversation(Base):
     __tablename__ = "conversations"
 
     id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
-    user_id = Column(UUID(as_uuid=True), nullable=False, index=True)
+    user_id = Column(UUID(as_uuid=True), ForeignKey("users.id"), nullable=False, index=True)
     customer_id = Column(UUID(as_uuid=True), ForeignKey("customers.id"), nullable=False, index=True)
     channel = Column(String(50), default="whatsapp")
     topic = Column(String(255))
@@ -66,7 +66,7 @@ class Message(Base):
     selected_suggestion = Column(Integer)
     user_edited = Column(Text)
     status = Column(String(50), default="sent")
-    metadata = Column(JSONB, default={})
+    msg_metadata = Column("metadata", JSONB, default={})
     created_at = Column(DateTime, default=datetime.utcnow)
 
     conversation = relationship("Conversation", back_populates="messages")