docs: add Remote Control troubleshooting guide for Pro/Max plan eligibility errors

[HarshalJain-cs]

Summary

Adds docs/remote-control-troubleshooting.md — a comprehensive community troubleshooting guide for the widespread Remote Control environments are not available for your account errors reported by Pro and Max plan users.

Motivation

This issue has generated 7+ duplicate issues with 100+ combined reactions in the past 4 days alone (#28817, #28816, #29037, #29185, #29449, #29638, #29980). The root cause is a combination of:

1. A docs inconsistency on code.claude.com/docs/en/remote-control: the page simultaneously states Remote Control is available on Pro plans AND that Pro support is "coming soon" — confusing users who think something is broken on their end when it may be a rollout limitation.

2. Legitimate local config issues (wrong auth method, conflicting env vars, leftover npm installs) that cause the same error for users who ARE eligible but have a misconfigured environment.

Issue #28817 is already assigned to @antrewmorrison with the area:docs label, confirming this is a known docs/comms gap.

What this PR adds

docs/remote-control-troubleshooting.md includes:

• Current rollout status table (Max: generally available, Pro: rollout in progress) with clarification of the contradictory docs statements
• All 4 error message variants and what each means
• 6-step troubleshooting checklist covering: auth method verification, env var conflicts, settings.json reset, version update, claude doctor check, full re-auth cycle
• Platform-specific notes for Windows, macOS, and Linux/WSL
• Related issues table linking all 7 tracking issues
• Next steps when no local fix works (wait for rollout, upgrade to Max, upvote tracking issue)

Related Issues

Closes / helps users in: #28817, #28816, #29037, #29185, #29449, #29638, #29980

Notes

• No source code changes — docs-only addition
• This complements (not replaces) the official docs update being tracked in [Bug] Remote Control unavailable despite Pro plan authentication #28817
• Can be merged independently; does not block any other work