test: comprehensive test coverage expansion (+965 tests)

Add 42 new test files covering all untested tool routes, image engine
internals, AI sidecar bridge, Zustand stores, and cross-format
compatibility. Expand e2e-docker suite with 7 spec files covering all
48 tools against a real Docker container.

Unit tests:
- Image engine: format detection, MIME mapping, metadata parsing, pipeline
- AI bridge: sidecar lifecycle, all 11 tool functions (mocked)
- Web stores: 14 Zustand stores (collage, settings, features, analytics, etc.)
- API helpers: format decoders, page range, file validation

Integration tests:
- 25 tool routes that had zero dedicated tests
- Cross-format matrix: 17 input formats x 3 tools
- Edge cases: zero-byte files, corrupted headers, path traversal, XSS, SQL injection
- Concurrent request handling and pipeline edge cases

E2E-Docker (Playwright against real container):
- 7 spec files: essential, adjustment, conversion, creative, utility, AI, pipeline
- Custom buildMultipart helper for multi-file tool uploads
- AI tools gracefully skip when sidecar not installed

Fixtures:
- Organized test media: formats/ (18 formats) + content/ (17 content types)
- Reduced from 3.1 GB unorganized samples to 33 MB structured fixtures

Bug fix:
- color-adjustments: gamma exposure used invalid single-param gamma() for
  positive values; fixed to use two-param gamma(gammaIn, gammaOut) form

tests/integration/image-to-pdf.test.ts

@@ -0,0 +1,196 @@
+/**
+ * Integration tests for the image-to-pdf tool.
+ *
+ * Converts one or more images into a PDF document. Custom route that
+ * accepts multiple file uploads and settings for page size, orientation,
+ * and margin.
+ */
+
+import { readFileSync } from "node:fs";
+import { join } from "node:path";
+import { afterAll, beforeAll, describe, expect, it } from "vitest";
+import { buildTestApp, createMultipartPayload, loginAsAdmin, type TestApp } from "./test-server.js";
+
+const FIXTURES = join(__dirname, "..", "fixtures");
+const PNG = readFileSync(join(FIXTURES, "test-200x150.png"));
+const JPG = readFileSync(join(FIXTURES, "test-100x100.jpg"));
+
+let testApp: TestApp;
+let app: TestApp["app"];
+let adminToken: string;
+
+beforeAll(async () => {
+  testApp = await buildTestApp();
+  app = testApp.app;
+  adminToken = await loginAsAdmin(app);
+}, 30_000);
+
+afterAll(async () => {
+  await testApp.cleanup();
+}, 10_000);
+
+describe("image-to-pdf", () => {
+  it("converts a single image to PDF", async () => {
+    const { body, contentType } = createMultipartPayload([
+      { name: "file", filename: "test.png", contentType: "image/png", content: PNG },
+      { name: "settings", content: JSON.stringify({}) },
+    ]);
+
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/tools/image-to-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+
+    expect(res.statusCode).toBe(200);
+    const json = JSON.parse(res.body);
+    expect(json.downloadUrl).toBeDefined();
+    expect(json.jobId).toBeDefined();
+    expect(json.pages).toBe(1);
+    expect(json.processedSize).toBeGreaterThan(0);
+  });
+
+  it("output is valid PDF (magic bytes)", async () => {
+    const { body, contentType } = createMultipartPayload([
+      { name: "file", filename: "test.png", contentType: "image/png", content: PNG },
+      { name: "settings", content: JSON.stringify({}) },
+    ]);
+
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/tools/image-to-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+
+    expect(res.statusCode).toBe(200);
+    const json = JSON.parse(res.body);
+
+    const dlRes = await app.inject({
+      method: "GET",
+      url: json.downloadUrl,
+      headers: { authorization: `Bearer ${adminToken}` },
+    });
+    expect(dlRes.statusCode).toBe(200);
+    const pdfBuffer = Buffer.from(dlRes.rawPayload);
+    // PDF files start with %PDF-
+    expect(pdfBuffer.subarray(0, 5).toString("ascii")).toBe("%PDF-");
+  });
+
+  it("converts multiple images to multi-page PDF", async () => {
+    const { body, contentType } = createMultipartPayload([
+      { name: "file", filename: "page1.png", contentType: "image/png", content: PNG },
+      { name: "file", filename: "page2.jpg", contentType: "image/jpeg", content: JPG },
+      { name: "settings", content: JSON.stringify({}) },
+    ]);
+
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/tools/image-to-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+
+    expect(res.statusCode).toBe(200);
+    const json = JSON.parse(res.body);
+    expect(json.pages).toBe(2);
+  });
+
+  it.each(["A4", "Letter", "A3", "A5"] as const)("supports page size: %s", async (pageSize) => {
+    const { body, contentType } = createMultipartPayload([
+      { name: "file", filename: "test.png", contentType: "image/png", content: PNG },
+      { name: "settings", content: JSON.stringify({ pageSize }) },
+    ]);
+
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/tools/image-to-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+
+    expect(res.statusCode).toBe(200);
+  });
+
+  it("supports landscape orientation", async () => {
+    const { body, contentType } = createMultipartPayload([
+      { name: "file", filename: "test.png", contentType: "image/png", content: PNG },
+      { name: "settings", content: JSON.stringify({ orientation: "landscape" }) },
+    ]);
+
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/tools/image-to-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+
+    expect(res.statusCode).toBe(200);
+  });
+
+  it("supports custom margin", async () => {
+    const { body, contentType } = createMultipartPayload([
+      { name: "file", filename: "test.png", contentType: "image/png", content: PNG },
+      { name: "settings", content: JSON.stringify({ margin: 50 }) },
+    ]);
+
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/tools/image-to-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+
+    expect(res.statusCode).toBe(200);
+  });
+
+  it("rejects request without any files", async () => {
+    const { body, contentType } = createMultipartPayload([
+      { name: "settings", content: JSON.stringify({}) },
+    ]);
+
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/tools/image-to-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+
+    expect(res.statusCode).toBe(400);
+    const json = JSON.parse(res.body);
+    expect(json.error).toContain("No image files");
+  });
+
+  it("rejects invalid settings JSON", async () => {
+    const { body, contentType } = createMultipartPayload([
+      { name: "file", filename: "test.png", contentType: "image/png", content: PNG },
+      { name: "settings", content: "not-json" },
+    ]);
+
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/tools/image-to-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+
+    expect(res.statusCode).toBe(400);
+  });
+
+  it("rejects margin out of range", async () => {
+    const { body, contentType } = createMultipartPayload([
+      { name: "file", filename: "test.png", contentType: "image/png", content: PNG },
+      { name: "settings", content: JSON.stringify({ margin: 999 }) },
+    ]);
+
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/tools/image-to-pdf",
+      headers: { authorization: `Bearer ${adminToken}`, "content-type": contentType },
+      body,
+    });
+
+    expect(res.statusCode).toBe(400);
+  });
+});