feat: sessions page workspace-first flow + workspace instance chips

- Sessions page: replaced CreateSessionForm with workspace selector + ToolStarter
  - Fetches workspaces, shows dropdown, then renders ToolStarter for selected workspace
  - Removed old project/repo/tool-type/config-profile/clone-mode flow
- Workspace cards: new WorkspaceInstanceChips component fetches and displays
  running instances per workspace with status-colored chips and open links
- Styles: .instance-chip variants (running/starting/error), .tool-starter-header

Quality gates: tsc --noEmit clean, pytest workspaces API (9 passed, 1 skipped)

apps/web/src/components/workspace-card.tsx

@@ -2,6 +2,7 @@
 
 import { Link } from "react-router-dom";
 import { Icon } from "./icon";
+import { WorkspaceInstanceChips } from "./workspace-instance-chips";
 import type { Workspace } from "../types/workspace";
 
 export interface WorkspaceCardProps {
@@ -46,12 +47,7 @@ export function WorkspaceCard({
 				<p className="workspace-branch">
 					<Icon name="branch" size="sm" /> {workspace.branch}
 				</p>
-				{workspace.instance_count > 0 && (
-					<p className="workspace-instances">
-						{workspace.instance_count} active tool
-						{workspace.instance_count > 1 ? "s" : ""}
-					</p>
-				)}
+				<WorkspaceInstanceChips workspaceId={workspace.id} />
 			</div>
 			<div className="workspace-actions">
 				<button