fix: Match state trigger/condition semantics to HA (#2565)

* Closes #2530

tests/utils/zod/forward-issues.test.ts

@@ -0,0 +1,40 @@
+import { describe, expect, it } from 'vitest';
+import { z } from 'zod';
+
+import { forwardIssues } from '../../../src/utils/zod/forward-issues';
+
+// Parse `value` through a schema whose `superRefine` delegates to
+// `forwardIssues`, returning the resulting error (or null on success).
+const runThrough = (
+  value: unknown,
+  target: z.ZodType,
+  path?: PropertyKey[],
+): z.ZodError | null => {
+  const result = z
+    .unknown()
+    .superRefine((v, ctx) => forwardIssues(ctx, v, target, path))
+    .safeParse(value);
+  return result.success ? null : result.error;
+};
+
+describe('forwardIssues', () => {
+  it('should add no issues when the value satisfies the schema', () => {
+    expect(runThrough('on', z.string())).toBeNull();
+  });
+
+  it('should forward issues with the given path prefix', () => {
+    const error = runThrough(5, z.string(), ['field']);
+    expect(error?.issues).toHaveLength(1);
+    expect(error?.issues[0].path).toEqual(['field']);
+  });
+
+  it('should forward at the issue path when no prefix is given', () => {
+    const error = runThrough(5, z.string());
+    expect(error?.issues[0].path).toEqual([]);
+  });
+
+  it('should prepend the prefix to nested issue paths', () => {
+    const error = runThrough({ inner: 5 }, z.object({ inner: z.string() }), ['outer']);
+    expect(error?.issues[0].path).toEqual(['outer', 'inner']);
+  });
+});