refactor(core): expose debuggableFn for effects in signal debug graph

Exposes the internal fn reference of effect reactive nodes on DebugSignalGraphNode as debuggableFn. This allows Angular DevTools to inspect and set breakpoints on effect callbacks.

packages/core/src/render3/util/signal_debug.ts

@@ -104,6 +104,14 @@ function getNodesAndEdgesFromSignalMap(signalMap: ReadonlyMap<ReactiveNode, Reac
         debuggableFn: consumer.lView?.[CONTEXT]?.constructor as (() => unknown) | undefined,
         id,
       });
+    } else if (isEffectNode(consumer)) {
+      debugSignalGraphNodes.push({
+        label: consumer.debugName,
+        kind: consumer.kind,
+        epoch: consumer.version,
+        debuggableFn: consumer.fn,
+        id,
+      });
     } else {
       debugSignalGraphNodes.push({
         label: consumer.debugName,

packages/core/test/acceptance/signal_debug_spec.ts

@@ -116,6 +116,8 @@ describe('getSignalGraph', () => {
 
     const effectNode = nodes.find((node) => node.label === 'primitiveSignalEffect')!;
     expect(effectNode).toBeDefined();
+    expect(effectNode.debuggableFn).toBeDefined();
+    expect(typeof effectNode.debuggableFn).toBe('function');
 
     const signalNode = nodes.find((node) => node.label === 'primitiveSignal')!;
     expect(signalNode).toBeDefined();