fix: add CI timeouts for slow image-enhancement tests

Image enhancement involves CLAHE + histogram analysis + multi-step
corrections, which exceeds the default 30s vitest timeout on GitHub
Actions runners. Add 120s timeouts for image-enhancement tests
(large file, HEIF input, format-matrix cross-format).

tests/integration/format-matrix-comprehensive.test.ts

@@ -188,8 +188,10 @@ function needsFallback(fmt: FormatDef): boolean {
   return fmt.needsCliDecoder || fmt.needsHeifDecoder || fmt.mayFailValidation;
 }
 
-function getTimeout(fmt: FormatDef): number | undefined {
-  return fmt.needsHeifDecoder || fmt.needsCliDecoder ? 180_000 : undefined;
+function getTimeout(fmt: FormatDef, toolId?: string): number | undefined {
+  if (fmt.needsHeifDecoder || fmt.needsCliDecoder) return 180_000;
+  if (toolId === "image-enhancement") return 120_000;
+  return undefined;
 }
 
 // ---------------------------------------------------------------------------
@@ -639,7 +641,7 @@ describe("Image enhancement across all 16 primary formats", () => {
             if (!res) return;
             assertDownloadResponse(res, fmt);
           },
-          getTimeout(fmt),
+          getTimeout(fmt, "image-enhancement"),
         );
       }
     });
@@ -896,7 +898,7 @@ describe("No-crash matrix: 16 formats x 12 tools", () => {
               expect(body.error.length).toBeGreaterThan(0);
             }
           },
-          getTimeout(fmt),
+          getTimeout(fmt, tool.id),
         );
       }
     });

tests/integration/format-matrix.test.ts

@@ -484,7 +484,12 @@ describe("Cross-format matrix", () => {
         // Skip "Convert to PNG" when input is already PNG (no-op conversion)
         if (tool.id === "convert" && fmt.name === "PNG") continue;
 
-        const perTestTimeout = fmt.needsHeifDecoder || fmt.needsCliDecoder ? 180_000 : undefined;
+        const perTestTimeout =
+          fmt.needsHeifDecoder || fmt.needsCliDecoder
+            ? 180_000
+            : tool.id === "image-enhancement"
+              ? 120_000
+              : undefined;
 
         it(
           `${tool.label}`,

tests/integration/image-enhancement.test.ts

@@ -609,7 +609,7 @@ describe("Alpha channel preservation", () => {
 
 // ── Large file handling ─────────────────────────────────────────
 describe("Large file handling", () => {
-  it("enhances a large stress image", async () => {
+  it("enhances a large stress image", { timeout: 120_000 }, async () => {
     const large = readFileSync(join(FIXTURES, "content", "stress-large.jpg"));
     const res = await postTool(
       { mode: "auto", intensity: 50 },
@@ -951,7 +951,7 @@ describe("Invalid image data", () => {
 
 // ── Large file with specific modes ──────────────────────────────
 describe("Large file with modes", () => {
-  it("enhances large image in low-light mode", async () => {
+  it("enhances large image in low-light mode", { timeout: 120_000 }, async () => {
     const large = readFileSync(join(FIXTURES, "content", "stress-large.jpg"));
     const res = await postTool(
       { mode: "low-light", intensity: 70 },
@@ -964,7 +964,7 @@ describe("Large file with modes", () => {
     expect(result.processedSize).toBeGreaterThan(0);
   });
 
-  it("enhances large image in document mode", async () => {
+  it("enhances large image in document mode", { timeout: 120_000 }, async () => {
     const large = readFileSync(join(FIXTURES, "content", "stress-large.jpg"));
     const res = await postTool(
       { mode: "document", intensity: 90 },