feat(browser): add extraArgs config for custom Chrome launch arguments

Adds a `browser.extraArgs` config option (string array) that is appended
to Chrome's launch arguments. This enables users to add stealth flags,
window size overrides, custom user-agent strings, or other Chrome flags
without patching the source code.

Example config:
  browser.extraArgs: ["--window-size=1920,1080", "--disable-infobars"]

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

src/browser/chrome.ts

@@ -217,6 +217,11 @@ export async function launchOpenClawChrome(
     // Stealth: hide navigator.webdriver from automation detection (#80)
     args.push("--disable-blink-features=AutomationControlled");
 
+    // Append user-configured extra arguments (e.g., stealth flags, window size)
+    if (resolved.extraArgs.length > 0) {
+      args.push(...resolved.extraArgs);
+    }
+
     // Always open a blank tab to ensure a target exists.
     args.push("about:blank");
 

src/browser/config.ts

@@ -31,6 +31,7 @@ export type ResolvedBrowserConfig = {
   attachOnly: boolean;
   defaultProfile: string;
   profiles: Record<string, BrowserProfileConfig>;
+  extraArgs: string[];
 };
 
 export type ResolvedBrowserProfile = {
@@ -196,6 +197,10 @@ export function resolveBrowserConfig(
       ? DEFAULT_BROWSER_DEFAULT_PROFILE_NAME
       : DEFAULT_OPENCLAW_BROWSER_PROFILE_NAME);
 
+  const extraArgs = Array.isArray(cfg?.extraArgs)
+    ? cfg.extraArgs.filter((a): a is string => typeof a === "string" && a.trim().length > 0)
+    : [];
+
   return {
     enabled,
     evaluateEnabled,
@@ -212,6 +217,7 @@ export function resolveBrowserConfig(
     attachOnly,
     defaultProfile,
     profiles,
+    extraArgs,
   };
 }