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/routes/index.tsx

@@ -45,7 +45,8 @@ function DashboardPage() {
 					]}
 				/>
 				<DashboardCard
-					to="/setups"
+					to="/collection"
+					search={{ tab: "setups" }}
 					title="Setups"
 					icon="tent"
 					stats={[{ label: "Setups", value: String(setupCount) }]}