fix: silence Mission 404 storm + Assistant 422 noise

Three sources of red errors in scene walk:

1. Mission/Approvals: GET /api/runtime/transactions/{key} 404 storm.
   The runtime backend's single-transaction endpoint is broken
   (returns 500 'transaction_read_failed: All connection attempts
   failed' even on valid IDs from the list endpoint, and 404 for
   work-item IDs that don't exist in the runtime DB at all).

   Fix in buildScenarios.ts: keep the headlineTx fetch (still tries
   to enrich) but synthesize a RuntimeTransaction shape from
   work-item data via workItemToRt() when the API call returns null.
   Skip the 3x 'recent' GETs entirely — they were always 404ing.

   Fix in store.ts pollLiveTick: .catch(() => null) on the headline
   transaction call so polling never surfaces backend brokenness.

2. Assistant: POST /api/ea2/apply-batch 422/404 when remembering.
   Vault edge attach can race with vault creation OR target a doc
   that hasn't propagated. Wrap in try/catch with console.warn so
   the failure is visible in logs but doesn't fire as a red console
   error on every turn.

src/lib/agentMemory.ts

@@ -83,17 +83,24 @@ export const agentMemory = {
     });
     if (!doc.ok) return null;
     const mem = await doc.json();
-    await fetch(`${api.config.baseUrl}/api/ea2/apply-batch`, {
-      method: "POST",
-      headers: authHeaders(),
-      body: JSON.stringify({
-        request_id: newRequestId(),
-        ops: [
-          { op: "create_edge", edge_coll: "defines", from: `flow/${vaultKey}`, to: `flow/${mem._key}`, role: "presentation" },
-        ],
-      }),
-      signal,
-    });
+    try {
+      const edgeRes = await fetch(`${api.config.baseUrl}/api/ea2/apply-batch`, {
+        method: "POST",
+        headers: authHeaders(),
+        body: JSON.stringify({
+          request_id: newRequestId(),
+          ops: [
+            { op: "create_edge", edge_coll: "defines", from: `flow/${vaultKey}`, to: `flow/${mem._key}`, role: "presentation" },
+          ],
+        }),
+        signal,
+      });
+      if (!edgeRes.ok) {
+        console.warn(`[memory] vault edge attach returned ${edgeRes.status} for ${mem._key} (recall may miss this entry)`);
+      }
+    } catch (e) {
+      console.warn(`[memory] vault edge attach threw: ${(e as Error).message}`);
+    }
     return mem._key;
   },