feat: add instance list component and integrate into workspace

- Create InstanceList component with create/start/stop/restart/delete
- Add tool instance icons (external, play, stop)
- Integrate InstanceList into RepoWorkspace sidebar
- Load tool types for instance creation
- Add instance-specific CSS styles

Quality gates: typecheck ✓, lint ✓, build ✓

apps/web/src/utils/icons.ts

@@ -28,6 +28,9 @@ import {
   Image,
   Binary,
   Code,
+  ArrowSquareOut,
+  Play,
+  Stop,
 } from "@phosphor-icons/react";
 
 export type IconName =
@@ -64,7 +67,10 @@ export type IconName =
   | "code"
   | "document"
   | "image"
-  | "binary";
+  | "binary"
+  | "external"
+  | "play"
+  | "stop";
 
 export const iconRegistry: Record<
   IconName,
@@ -113,6 +119,11 @@ export const iconRegistry: Record<
   document: FileText,
   image: Image,
   binary: Binary,
+
+  // Instance actions
+  external: ArrowSquareOut,
+  play: Play,
+  stop: Stop,
 };
 
 export const iconCategories = {