perf: switch to domcontentloaded default, optimize browser pool, fix swagger paths

Performance fixes:
- Default waitUntil changed from networkidle2 to domcontentloaded (saves ~500ms+)
- Add waitUntil parameter so users can choose (load/domcontentloaded/networkidle0/networkidle2)
- Optimize page recycle: use DOM reset instead of about:blank navigation
- Add Chromium flags to disable unnecessary features (background networking, extensions, sync, etc.)

Swagger fixes:
- Fix apis glob to include dist/*.js (was only matching src/*.ts, empty at runtime)
- Document new waitUntil parameter on POST /v1/screenshot
- Add OpenAPI docs for /status endpoint

src/services/screenshot.ts

@@ -13,6 +13,7 @@ export interface ScreenshotOptions {
   waitForSelector?: string;
   deviceScale?: number;
   delay?: number;
+  waitUntil?: "load" | "domcontentloaded" | "networkidle0" | "networkidle2";
 }
 
 export interface ScreenshotResult {
@@ -34,6 +35,7 @@ export async function takeScreenshot(opts: ScreenshotOptions): Promise<Screensho
   const fullPage = opts.fullPage ?? false;
   const quality = format === "png" ? undefined : Math.min(Math.max(opts.quality || 80, 1), 100);
   const deviceScale = Math.min(opts.deviceScale || 1, 3);
+  const waitUntil = opts.waitUntil || "domcontentloaded";
 
   const { page, instance } = await acquirePage();
 
@@ -42,7 +44,7 @@ export async function takeScreenshot(opts: ScreenshotOptions): Promise<Screensho
 
     await Promise.race([
       (async () => {
-        await page.goto(opts.url, { waitUntil: "networkidle2", timeout: 20_000 });
+        await page.goto(opts.url, { waitUntil, timeout: 20_000 });
 
         if (opts.waitForSelector) {
           await page.waitForSelector(opts.waitForSelector, { timeout: 10_000 });