fix(core): visit ng-let expression value in signal migration schematics

Before this fix, references to inputs inside @let statements were not
accounted for.

packages/core/schematics/migrations/signal-migration/src/passes/reference_resolution/template_reference_visitor.ts

@@ -26,6 +26,7 @@ import {
   TmplAstDeferredBlock,
   TmplAstForLoopBlock,
   TmplAstIfBlockBranch,
+  TmplAstLetDeclaration,
   TmplAstNode,
   TmplAstRecursiveVisitor,
   TmplAstSwitchBlock,
@@ -223,6 +224,10 @@ export class TemplateReferenceVisitor<
       this.templateAttributeReferencedFields.push(...referencedFields);
     }
   }
+
+  override visitLetDeclaration(decl: TmplAstLetDeclaration): void {
+    this.checkExpressionForReferencedFields(decl, decl.value);
+  }
 }
 
 /**

packages/core/schematics/migrations/signal-migration/test/golden-test/template_ng_let.ts

@@ -0,0 +1,16 @@
+// tslint:disable
+
+import {Component, Input} from '@angular/core';
+
+@Component({
+  template: `
+    @let sum = one + two;
+    @let three = this.three;
+    {{ sum }} {{ three }}
+  `,
+})
+export class MyComp {
+  @Input() one = 1;
+  @Input() two = 2;
+  @Input() three = 3;
+}

packages/core/schematics/migrations/signal-migration/test/golden.txt

@@ -1257,6 +1257,24 @@ export class MyComp {
   readonly fourth = input(true);
   readonly fifth = input(true);
 }
+@@@@@@ template_ng_let.ts @@@@@@
+
+// tslint:disable
+
+import {Component, input} from '@angular/core';
+
+@Component({
+  template: `
+    @let sum = one() + two();
+    @let three = this.three();
+    {{ sum }} {{ three }}
+  `,
+})
+export class MyComp {
+  readonly one = input(1);
+  readonly two = input(2);
+  readonly three = input(3);
+}
 @@@@@@ template_object_shorthand.ts @@@@@@
 
 // tslint:disable

packages/core/schematics/migrations/signal-migration/test/golden_best_effort.txt

@@ -1211,6 +1211,24 @@ export class MyComp {
   readonly fourth = input(true);
   readonly fifth = input(true);
 }
+@@@@@@ template_ng_let.ts @@@@@@
+
+// tslint:disable
+
+import {Component, input} from '@angular/core';
+
+@Component({
+  template: `
+    @let sum = one() + two();
+    @let three = this.three();
+    {{ sum }} {{ three }}
+  `,
+})
+export class MyComp {
+  readonly one = input(1);
+  readonly two = input(2);
+  readonly three = input(3);
+}
 @@@@@@ template_object_shorthand.ts @@@@@@
 
 // tslint:disable