Allow 'bypass permissions' toggle (Shift+Tab) in agent sessions or /bg background jobs

Problem

When working in an agent session or a /bg background job, there is no way to activate the "bypass permissions on" mode using the Shift+Tab cycle shortcut. This shortcut works correctly in normal interactive sessions, but is unavailable in agent/background contexts.

Current behavior

• In a normal Claude Code session: Shift+Tab cycles through permission modes, including enabling "bypass permissions on"
• In an agent session or /bg background work: the Shift+Tab cycle is not available, so you cannot toggle bypass permissions

Expected behavior

The Shift+Tab permission mode cycling (including "bypass permissions on") should be available in all session types:

• Normal interactive sessions (already works)
• Agent sessions (currently missing)
• /bg background jobs (currently missing)

Why this matters

Agent sessions and background jobs are the contexts where permission prompts cause the most friction — the user may not be actively watching, or the agent may be doing repetitive operations across many files. Being able to opt into bypass mode in these contexts would significantly improve the workflow for trusted, known-safe operations.

Suggested approach

Expose the same Shift+Tab permission cycling UI that exists in interactive sessions to agent and /bg session contexts, so the user can opt in before the agent starts working.