Feature request: expose CLAUDE_REMOTE_CONTROL env var in Bash tool when remote control is active

Problem

When Claude Code is used via the Anthropic app's remote control feature, tools like AskUserQuestion render interactive terminal UIs (arrow keys + Enter to select) that the user cannot interact with — the remote control interface only supports text input.

Third-party skills (e.g., gstack) need a way to detect remote control mode so they can gracefully degrade to plain text alternatives.

Current workarounds (and why they fail)

• TTY detection (tty / test -t 0): Claude Code's Bash tool never has a real TTY attached, so this always reports "no TTY" — even in normal terminal mode. Unreliable.
• Session token inspection: The JWT contains "application": "ccr" for remote control sessions, but this persists even after disconnecting. Not real-time.
• Manual toggle: Works but requires users to remember to enable/disable. Poor UX.

Proposed solution

Set an environment variable in the Bash tool's execution environment when remote control is active:

CLAUDE_REMOTE_CONTROL=1

This would allow any tool, skill, or script to detect remote control mode and adapt behavior accordingly (e.g., fall back to plain text questions instead of interactive TUI prompts).

Context

• gstack PR implementing the manual workaround: https://github.com/garrytan/gstack/pull/459
• This likely affects any Claude Code skill/tool that uses AskUserQuestion or other interactive terminal features