fix(ui): never leave a lineage graph or its controls hidden

Each first-fit attempt is bounded by a frame, so a fit the flow never runs
cannot keep the graph hidden, and an empty graph shows its controls.

Author: kvlonge

ui/src/lib/lineage/flow-controller.svelte

@@ -25,11 +25,12 @@
 			void flow.fitView({ duration: 300, padding: 0.08, maxZoom: 1, ...opts });
 			return;
 		}
-		// Until the graph has been shown, fit without animating, so it appears already in place. A fit fails
-		// while cards are still being measured, so it is retried, and the graph shows only after a fit has painted.
+		// Until the graph has been shown, fit without animating, so it appears already in place. A fit waits
+		// until the flow can run it, so each try is bounded by a frame; after 20 the graph shows regardless.
 		void (async () => {
 			for (let attempt = 0; attempt < 20 && !fitted; attempt++) {
-				if (await flow.fitView({ padding: 0.08, maxZoom: 1, ...opts, duration: 0 })) {
+				const fit = flow.fitView({ padding: 0.08, maxZoom: 1, ...opts, duration: 0 });
+				if (await Promise.race([fit, frame().then(() => false)])) {
 					await frame();
 					await frame();
 					fitted = true;

ui/src/lib/lineage/scope-graph.svelte

@@ -57,7 +57,7 @@
 	});
 </script>
 
-<div class="graph sb-flow" class:unfitted={!fitted}>
+<div class="graph sb-flow" class:unfitted={!fitted && nodes.length > 0}>
 	<SvelteFlow
 		bind:nodes
 		bind:edges

ui/src/lib/lineage/scoped-lineage.svelte

@@ -192,7 +192,7 @@
 	</div>
 
 	<!-- graph -->
-	<div class="sb-flow relative min-h-0 flex-1" class:unfitted={!fitted} style="background: var(--sb-inset)">
+	<div class="sb-flow relative min-h-0 flex-1" class:unfitted={!fitted && nodes.length > 0} style="background: var(--sb-inset)">
 		<SvelteFlow
 			bind:nodes
 			bind:edges