test: reorganize flat test files into purpose-based subdirectories (phase 6)

Group 245 flat integration tests and 25 loose unit tests into
discoverable subdirectories per spec section 6:

  integration/tools/{image,video,audio,document,data}/  (156 files)
  integration/platform/                                  (64 files)
  integration/generated/                                 (14 files)
  integration/security/                                  (10 files)

  unit/security/     (8 files, new subdir)
  unit/api/          (7 files moved in)
  unit/web/          (3 files moved in)
  unit/shared/       (6 files moved in)
  unit/image-engine/ (1 file moved in)

All moves via git mv (history preserved). Relative imports repaired
for both depth levels (platform/generated/security = +1, tools/ = +2):
static from-imports, dynamic import() calls, vi.mock() paths,
import.meta.dirname joins, and __dirname joins.

Vitest discovery unchanged (no test.include in config, recursive glob
matches subdirs, shard-by-hash unaffected). test-server.ts and
tool-route-drift.test.ts stay at integration root. fixtures/ untouched.

Parity gate: 13189 passing test names before = 13189 after (0 dropped).

tests/integration/tools/video/stabilize-video.test.ts

@@ -0,0 +1,97 @@
+import { mkdtempSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { ffmpegAvailable, probeMedia } from "@snapotter/media-engine";
+import { afterAll, beforeAll, describe, expect, it } from "vitest";
+import { fixtures, readFixture } from "../../../fixtures/index.js";
+import {
+  buildTestApp,
+  createMultipartPayload,
+  loginAsAdmin,
+  type TestApp,
+} from "../../test-server.js";
+
+const MP4 = readFixture(fixtures.video.tiny("mp4"));
+
+let testApp: TestApp;
+let adminToken: string;
+
+beforeAll(async () => {
+  testApp = await buildTestApp();
+  adminToken = await loginAsAdmin(testApp.app);
+}, 30_000);
+
+afterAll(async () => {
+  await testApp.cleanup();
+}, 10_000);
+
+async function runTool(settings: Record<string, unknown> = {}) {
+  const { body, contentType } = createMultipartPayload([
+    { name: "file", filename: "tiny.mp4", contentType: "video/mp4", content: MP4 },
+    { name: "settings", content: JSON.stringify(settings) },
+  ]);
+  return testApp.app.inject({
+    method: "POST",
+    url: "/api/v1/tools/stabilize-video",
+    headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+    body,
+  });
+}
+
+/**
+ * Handles both the 200 sync-window path and the 202+poll path.
+ * Long-hint tools may complete within the sync window (200) or go async (202).
+ */
+async function resolveResult(res: Awaited<ReturnType<typeof runTool>>): Promise<{
+  path: "sync" | "poll";
+  downloadPayload: Buffer;
+}> {
+  if (res.statusCode === 200) {
+    const envelope = JSON.parse(res.body);
+    expect(envelope.downloadUrl).toBeDefined();
+    const dl = await testApp.app.inject({ method: "GET", url: envelope.downloadUrl });
+    expect(dl.statusCode).toBe(200);
+    return { path: "sync", downloadPayload: dl.rawPayload };
+  }
+
+  expect(res.statusCode).toBe(202);
+  const { jobId } = JSON.parse(res.body);
+  expect(jobId).toBeDefined();
+
+  const { db, schema } = await import("../../../../apps/api/src/db/index.js");
+  const { eq } = await import("drizzle-orm");
+  let row: { status: string; outputRefs: unknown } | undefined;
+  for (let i = 0; i < 120; i++) {
+    [row] = await db.select().from(schema.jobs).where(eq(schema.jobs.id, jobId));
+    if (row && ["completed", "failed", "canceled"].includes(row.status)) break;
+    await new Promise((r) => setTimeout(r, 500));
+  }
+  expect(row?.status).toBe("completed");
+  const outName = (row?.outputRefs as string[])[0].split("/").pop() as string;
+  const dl = await testApp.app.inject({
+    method: "GET",
+    url: `/api/v1/download/${jobId}/${encodeURIComponent(outName)}`,
+  });
+  expect(dl.statusCode).toBe(200);
+  return { path: "poll", downloadPayload: dl.rawPayload };
+}
+
+describe.skipIf(!ffmpegAvailable())("stabilize-video (requires ffmpeg)", () => {
+  it("stabilizes a video and returns a downloadable mp4", async () => {
+    const res = await runTool({});
+    const { downloadPayload } = await resolveResult(res);
+    expect(downloadPayload.length).toBeGreaterThan(100);
+
+    const tmpDir = mkdtempSync(join(tmpdir(), "stab-test-"));
+    const probeFile = join(tmpDir, "stabilized.mp4");
+    writeFileSync(probeFile, downloadPayload);
+    const info = await probeMedia(probeFile);
+    const v = info.streams.find((s) => s.type === "video");
+    expect(v).toBeDefined();
+  }, 120_000);
+
+  it("rejects smoothing out of range with 400", async () => {
+    const res = await runTool({ smoothing: 100 });
+    expect(res.statusCode).toBe(400);
+  });
+});