Add guidance for WorkTrunk hook approvals in non-interactive Codex flows

[adrianmross]

Problem

wt merge and other commands can stop on hook approval prompts in non-interactive Codex sessions. This is especially visible when a repo uses pre-merge validation hooks.

Proposal

• Document wt config approvals add / approvals file usage for trusted hooks
• Document when to use --yes versus pre-approvals
• Add a Codex-specific troubleshooting section for non-interactive hook approval failures
• Consider a command doc for diagnosing approval blockers

Why

This is a high-friction failure mode for Codex users working through WorkTrunk-managed repos.