feat(central-ui): FlowGraphView External lane, outbound status pills, async/spawn connectors

Four lanes (LaneCount 4; External sublabel = distinct targets, three then +n);
ApiCall/DbCall/Notify nodes carry a status pill (Ok/Pending/Parked/Failed —
pending pulses, reduced-motion aware) plus a sync/cached/notify mode; folded
lifecycles show '+4.1 s' submit→terminal wall time. Async edges are dashed
and routed through the inter-lane strip with a gutter tag; spawn edges use a
bolt marker. Predicted async edges (Task 6's PredictedEdge.Async) render the
same way. de-DE height pinned at 319.2 = (4×110+16)×0.7.

Claude-Session: https://claude.ai/code/session_01NcMG6xXdsJbmD2wYAgkK29

docs/plans/2026-09-06-flow-debugger-outbound-calls.md.tasks.json

@@ -34,7 +34,7 @@
     {
       "id": 4,
       "subject": "Task 4: Central \u2014 audit InboundDatabaseHelper (DbOutbound) and feed the trace sink",
-      "status": "in_progress",
+      "status": "completed",
       "blockedBy": [
         0
       ]
@@ -50,7 +50,7 @@
     {
       "id": 6,
       "subject": "Task 6: FlowShapePredictor \u2014 three kinds on the External lane, async edges",
-      "status": "in_progress",
+      "status": "completed",
       "blockedBy": [
         0
       ]
@@ -96,5 +96,5 @@
       ]
     }
   ],
-  "lastUpdated": "2026-09-06T05:51:19.355720+00:00"
+  "lastUpdated": "2026-09-06T05:52:50.321199+00:00"
 }