* 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.