## Why

The current tool configuration page (`/tool-configs`) presents all configs in a flat list with a basic form. As the number of tool types and configuration options grows, this becomes unwieldy. Users need a more organized way to browse, edit, and manage configurations per tool type.

## What Changes

- **Rework the tool config UI** from a flat list to a **split-pane layout**: list of tool configs on the left, detail/edit panel on the right
- **Add new config fields**: `start_command`, `port`, `working_directory`, `environment_variables` (JSON), `volumes` (JSON)
- **Update backend model** to support these new fields
- **Create database migration** for the new columns
- **Update API endpoints** to handle new fields
- **Update frontend types and API client**
- **Redesign the page** with proper navigation and editing experience

## Capabilities

### New Capabilities
- `tool-config-management`: Enhanced tool configuration management with extended fields and split-pane UI

### Modified Capabilities
- `tool-types`: Tool type display will show associated configs in the new UI (presentation layer change only, no API changes)

## Impact

- **Backend**: `tool_configs` model, API endpoints, database migration
- **Frontend**: Complete rework of `ToolConfigsPage` component, new types, updated API client
- **Database**: New columns on `tool_configs` table
- **User Experience**: Significantly improved configuration management workflow