fix(cli): consolidate snapshot and frame diagnostics (#2402)

* fix(snapshot): preserve exact requested times

* fix(cli): fail video snapshots without FFmpeg

* fix(cli): honor navigation timeout in diagnostics

* fix(cli): preserve snapshot alpha and create shot dirs

packages/cli/src/commands/keyframes.test.ts

@@ -1,9 +1,10 @@
-import { mkdtempSync, mkdirSync, writeFileSync } from "node:fs";
+import { existsSync, mkdtempSync, mkdirSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { beforeAll, describe, expect, it } from "vitest";
 import { ensureDOMParser } from "../utils/dom.js";
 import { collectShotSelectors, resolveScope, surfaceComposition } from "./keyframes.js";
+import { ensureShotOutputDir } from "./motionShot.js";
 
 beforeAll(() => ensureDOMParser());
 
@@ -26,6 +27,15 @@ describe("keyframes direct composition scope", () => {
   });
 });
 
+describe("keyframes shot output", () => {
+  it("creates a missing parent directory before writing --shot", () => {
+    const projectDir = mkdtempSync(join(tmpdir(), "hf-keyframes-shot-dir-"));
+    const outputDir = join(projectDir, "nested", "proofs");
+    ensureShotOutputDir(join(outputDir, "shot.png"));
+    expect(existsSync(outputDir)).toBe(true);
+  });
+});
+
 describe("keyframes multi-stroke traces", () => {
   it("composites ≥2 position strokes on one element into a single trace", () => {
     const html = wrap(`