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/document/compress-pdf.test.ts

@@ -0,0 +1,58 @@
+import { gsAvailable } from "@snapotter/doc-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 PDF = readFixture(fixtures.document.pdf3);
+
+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);
+
+describe.skipIf(!gsAvailable())("compress-pdf (requires gs)", () => {
+  async function run(settings: Record<string, unknown>) {
+    const { body, contentType } = createMultipartPayload([
+      { name: "file", filename: "test-3page.pdf", contentType: "application/pdf", content: PDF },
+      { name: "settings", content: JSON.stringify(settings) },
+    ]);
+    return testApp.app.inject({
+      method: "POST",
+      url: "/api/v1/tools/compress-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+  }
+
+  async function expectValidPdf(res: Awaited<ReturnType<typeof run>>): Promise<number> {
+    expect(res.statusCode).toBe(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);
+    expect(dl.rawPayload.subarray(0, 5).toString()).toBe("%PDF-");
+    return dl.rawPayload.length;
+  }
+
+  it("compresses by quality and returns a valid PDF", async () => {
+    await expectValidPdf(await run({ mode: "quality", quality: 60 }));
+  }, 60_000);
+
+  it("compresses to a target size (DPI binary search) and returns a valid PDF", async () => {
+    // Output is content-dependent (text PDFs barely shrink), so assert a valid
+    // PDF rather than an exact size; this exercises the binary-search path.
+    await expectValidPdf(await run({ mode: "targetSize", targetSizeKb: 50 }));
+  }, 120_000);
+});