Add Charon Bankr skill

[CharonAI-code]

Adds the Charon Bankr skill.

Charon gives Bankr agents a policy checkpoint before executing actions with side effects. The skill includes:

• a normalized action model for code, shell, git, network, browser, automation, wallet, signing, and token actions
• editable PASS / PAUSE / DENY policy templates
• a deterministic policy checker script
• a receipt generation script
• references and examples for agents

Tested locally:

• protected code deletion returns DENY
• Transfer of WETH paused
• receipt generation returns a Charon receipt object