fix(browser-tools): make sharp an optional lazy dependency

sharp requires platform-specific native binaries and is unavailable
when running via bunx or on platforms like Raspberry Pi (ARM) where
the prebuilt binary may not exist.

The previous top-level static import caused the browser-tools extension
to crash at load time before any tool was ever called.

Replace the static import with a lazy getSharp() helper that catches
import failures and caches the result. constrainScreenshot returns the
raw buffer unchanged when sharp is unavailable — screenshots remain
functional, just without resizing.

The core bunx extension-loading fix (routing bunx through virtualModules
in loader.ts) belongs upstream in pi-mono and will be submitted there
once the OSS weekend freeze lifts on 2026-04-13.

Related: #3504

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/resources/extensions/browser-tools/capture.ts

@@ -6,7 +6,22 @@
  */
 
 import type { Frame, Page } from "playwright";
-import sharp from "sharp";
+
+// sharp is an optional native dependency. Load it lazily so that the extension
+// can still be loaded on platforms where sharp is unavailable (e.g. bunx on
+// Raspberry Pi). constrainScreenshot falls back to returning the raw buffer
+// when sharp is not installed, which means screenshots won't be resized but
+// the tool remains functional.
+let _sharp: typeof import("sharp") | null | undefined;
+async function getSharp(): Promise<typeof import("sharp") | null> {
+	if (_sharp !== undefined) return _sharp;
+	try {
+		_sharp = (await import("sharp")).default;
+	} catch {
+		_sharp = null;
+	}
+	return _sharp;
+}
 import type { CompactPageState, CompactSelectorState } from "./state.js";
 import { formatCompactStateSummary } from "./utils.js";
 
@@ -168,6 +183,9 @@ export async function constrainScreenshot(
 	mimeType: string,
 	quality: number,
 ): Promise<Buffer> {
+	const sharp = await getSharp();
+	if (!sharp) return buffer;
+
 	const meta = await sharp(buffer).metadata();
 	const width = meta.width;
 	const height = meta.height;