refactor: move setups list into collection page as third tab

Setups now lives alongside My Gear and Planning under /collection?tab=setups
instead of its own /setups route. Dashboard card updated to link to the new
tab. Setup detail pages (/setups/:id) remain unchanged.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/client/components/ThreadTabs.tsx

@@ -1,14 +1,17 @@
-interface ThreadTabsProps {
-	active: "gear" | "planning";
-	onChange: (tab: "gear" | "planning") => void;
+type TabKey = "gear" | "planning" | "setups";
+
+interface CollectionTabsProps {
+	active: TabKey;
+	onChange: (tab: TabKey) => void;
 }
 
 const tabs = [
 	{ key: "gear" as const, label: "My Gear" },
 	{ key: "planning" as const, label: "Planning" },
+	{ key: "setups" as const, label: "Setups" },
 ];
 
-export function ThreadTabs({ active, onChange }: ThreadTabsProps) {
+export function CollectionTabs({ active, onChange }: CollectionTabsProps) {
 	return (
 		<div className="flex border-b border-gray-200">
 			{tabs.map((tab) => (