Persist capture data per session (field values, schema, links)

Capture mode state lived only in React memory and was lost when
reopening a session or remounting EngineProvider.

- Add per-session localStorage capture snapshot (schema, values, links)
- Restore on session mount; persist on field/schema/link changes
- Seed binder links from storage without spurious bus events
- Clean up capture key when session is deleted
- Integration test for reload persistence

src/app/forms/CaptureLinkPersister.tsx

@@ -0,0 +1,29 @@
+/**
+ * Writes evidence links to per-session capture storage whenever the
+ * binder mutates links.
+ */
+
+import { useEffect } from "react";
+
+import type { SessionId } from "@shared/ids";
+
+import { useBinder } from "@binder/index";
+import { useEngineEventTick } from "@work/index";
+
+import { persistCapturePatch } from "./capture-persistence";
+
+export function CaptureLinkPersister({ sessionId }: { sessionId: SessionId }) {
+  const { links } = useBinder();
+  const linkTick = useEngineEventTick("EvidenceLinkCreated");
+  const unlinkTick = useEngineEventTick("EvidenceLinkRemoved");
+  const updateTick = useEngineEventTick("EvidenceLinkUpdated");
+
+  useEffect(() => {
+    void linkTick;
+    void unlinkTick;
+    void updateTick;
+    persistCapturePatch(sessionId, { evidenceLinks: links.list() });
+  }, [sessionId, links, linkTick, unlinkTick, updateTick]);
+
+  return null;
+}