* refactor: Remove unused imports and consolidate ephemeral agent logic
* refactor: Side Panel agent handling to account for ephemeral agents for UI
* refactor: Replace Constants.EPHEMERAL_AGENT_ID checks with isEphemeralAgent utility for consistency
* ci: AgentPanel tests with additional mock configurations and utility functions
* refactor: agent tool permissions to support ephemeral agent settings
* ci: rename render tests and correct typing for `useAgentToolPermissions` hook
* refactor: implement `DragDropContext` to minimize effect of `useChatContext` in `DragDropModal`
- Added isEphemeralAgent function to streamline checks for ephemeral agents.
- Updated logic in useAgentToolPermissions to utilize the new function for determining tool access.
- Introduced comprehensive tests for useAgentToolPermissions covering various scenarios including ephemeral agents, regular agents with tools, and edge cases.
