feat(enterprise): add query-governance commands

[xe-nvdk]

Context

Arc Enterprise query-governance policies and usage counters are only accessible through the REST API or SDK. arcli has token management, making governance a natural adjacent operator workflow.

Scope

Add a arcli governance command tree covering:

• policy list
• policy show
• policy create
• policy update
• policy delete
• usage

Map to /api/v1/governance/policies* and /api/v1/governance/usage/:token_id.

Acceptance criteria

• Token arguments accept numeric id or exact token name
• All policy limits supported by Arc can be set and displayed
• Limit values are validated as non-negative, preserving zero as unlimited
• List output supports table, JSON, and CSV; object output supports table and JSON
• Policy deletion prompts and supports --yes
• Enterprise-license, admin-permission, and not-found errors remain distinguishable
• Typed client and command tests cover policy CRUD, usage, validation, and errors
• README/help and release notes document the commands