feat: add --allow-file-access flag for file:// URL support (#375)

* feat: add --allow-file-access flag for file:// URL support

Adds the ability to open and interact with local files using file:// URLs.
This enables use cases like viewing local PDFs, testing local HTML files,
and allowing JavaScript to access other local files via XHR.

The flag adds Chromium's --allow-file-access-from-files and --allow-file-access
launch arguments. Only supported in Chromium browsers.

Fixes #345

* fix: add cli_allow_file_access tracking to prevent spurious warning

When --allow-file-access is set via AGENT_BROWSER_ALLOW_FILE_ACCESS env var
(not CLI), don't warn about the flag being ignored when daemon is already running.

src/types.ts

@@ -29,6 +29,7 @@ export interface LaunchCommand extends BaseCommand {
   userAgent?: string;
   provider?: string;
   ignoreHTTPSErrors?: boolean;
+  allowFileAccess?: boolean; // Enable file:// URL access and cross-origin file requests
 }
 
 export interface NavigateCommand extends BaseCommand {