Add reusable tools and assistant bindings

- Introduce a new `Tool` model and `AssistantToolBinding` for managing reusable tools within the application.
- Implement CRUD operations for tools in the new `tools` route, allowing for the creation, retrieval, updating, and deletion of tools.
- Update the `Assistant` model to include a list of tool IDs, enabling assistants to utilize these tools.
- Enhance the backend routes to synchronize tool bindings with assistants, ensuring proper management of tool associations.
- Add frontend components for tool management, including a tool picker in the assistant configuration, improving user experience in tool selection.
- Create a mobile call page to facilitate video calls, integrating camera and microphone selection for enhanced communication capabilities.
- Update API definitions to include tool-related types and operations, ensuring consistency across the application.
- Add a migration script to create the necessary database tables for tools and bindings, supporting the new functionality.

backend/db/models.py

@@ -145,3 +145,45 @@ class AssistantModelBinding(Base):
     updated_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
     )
+
+
+class Tool(Base):
+    """Reusable LLM tool definition. Runtime execution is added separately."""
+
+    __tablename__ = "tools"
+
+    id: Mapped[str] = mapped_column(String(40), primary_key=True)
+    name: Mapped[str] = mapped_column(String(128))
+    function_name: Mapped[str] = mapped_column(String(64), unique=True, index=True)
+    type: Mapped[str] = mapped_column(String(24), index=True)
+    description: Mapped[str] = mapped_column(String(2048), default="")
+    definition: Mapped[dict] = mapped_column(JSONB, default=dict)
+    secrets: Mapped[dict] = mapped_column(JSONB, default=dict)
+    status: Mapped[str] = mapped_column(String(16), index=True, default="active")
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now()
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
+    )
+
+
+class AssistantToolBinding(Base):
+    """Prompt assistant to reusable tool many-to-many binding."""
+
+    __tablename__ = "assistant_tool_bindings"
+
+    assistant_id: Mapped[str] = mapped_column(
+        String(40),
+        ForeignKey("assistants.id", ondelete="CASCADE"),
+        primary_key=True,
+    )
+    tool_id: Mapped[str] = mapped_column(
+        String(40),
+        ForeignKey("tools.id", ondelete="RESTRICT"),
+        primary_key=True,
+        index=True,
+    )
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now()
+    )