feat: enforce single tool type with port config

- Replace interfaces array with interface_type string and requires_port boolean
- Add database migration for schema change
- Update backend model, API schemas, and validation
- Update frontend types and tool workshop UI
- Add dropdown for interface type selection
- Conditionally show/hide port fields based on requires_port
- Update tests and mock data
- All frontend tests pass (37/37)
- Frontend typecheck and lint pass

apps/web/src/pages/tool-configs.tsx

@@ -170,7 +170,7 @@ export const ToolConfigsPage = () => {
         </select>
         {selectedTool && (
           <p className="muted" style={{ marginTop: "0.5rem" }}>
-            Category: {selectedTool.category} · Interfaces: {selectedTool.interfaces?.join(", ")}
+            Category: {selectedTool.category} · Interface: {selectedTool.interface_type}
           </p>
         )}
       </div>