fix(build): externalize socks + sharp in node-server bundle

Bun's bundler refused to inline socks and sharp (both ship
.node native addons), so the Windows node-server build
failed with 'Could not resolve: socks / sharp'.

Added --external socks and --external sharp to
browse/scripts/build-node-server.sh, matching the script's
own documented rule for .node-addon deps. Verified:
bash build-node-server.sh -> exit 0, emits server-node.mjs;
bun run build -> exit 0 (all 6 artifacts compile).

browse/scripts/build-node-server.sh

@@ -26,7 +26,9 @@ bun build "$SRC_DIR/server.ts" \
   --external playwright-core \
   --external diff \
   --external "bun:sqlite" \
-  --external "@ngrok/ngrok"
+  --external "@ngrok/ngrok" \
+  --external socks \
+  --external sharp
 
 # Step 2: Post-process
 # Replace import.meta.dir with a resolvable reference