fix: permission checks for external_directory and doom_loop

[AerionDyseti]

Summary

Fixes permission checks that were not properly enforcing deny settings, allowing operations to proceed when they should be blocked.

Root Cause

Permission checks across the codebase were using an insecure pattern:

• Only checking for "ask" or specific values
• Ignoring "deny" settings
• Allowing operations when permission was undefined, null, or any unexpected value
• System was fail-open instead of fail-secure

Testing

Added comprehensive unit tests covering:

• external_directory='allow' - proceeds without asking
• external_directory='deny' - denies without asking
• external_directory='ask' with approval - asks and proceeds
• external_directory='ask' with denial - asks and denies

All 196 tests passing.

Fixes a systemic issue that could allow agents to bypass configured permission restrictions.

[rekram1-node]

Thank u for spotting this, will tweak it and merge it, currently cant due to github outage

[AerionDyseti]

Just to confirm: this current code path is "fail open" which means that if they leave it empty or put any value other than "ask" or "deny", it will automatically approve. I just want to make sure that's intended.

[rekram1-node]

If you don't set it, it automatically asks as intended

If you set it to allow it will allow