fix: detect cmux sessions with ghostty env

[umputun]

Detect cmux sessions that expose Ghostty environment variables but no CMUX_SURFACE_ID, and route them through the cmux CLI launcher instead of the Ghostty AppleScript branch.

This updates the Claude, Codex, and plan-review launcher copies, adds focused launcher coverage for the cmux/Ghostty-env case, refreshes README/site/plugin docs, and bumps affected plugin/package versions.

Related to #202

[Copilot]

Pull request overview

This PR adjusts terminal-session detection so cmux sessions that inherit Ghostty environment variables (but don’t expose CMUX_SURFACE_ID) are still routed through the cmux CLI launcher path, avoiding the Ghostty AppleScript branch. This targets the cmux + Claude Code behavior described in #202 and keeps the various launcher copies and docs in sync.

Changes:

• Add is_cmux_session detection (via CMUX_SURFACE_ID, __CFBundleIdentifier, and Ghostty env paths containing cmux.app) and use it to gate the cmux CLI branch ahead of Ghostty.
• Extend launcher tests to cover the “cmux session with Ghostty env vars” scenario.
• Update README/site/plugin docs and bump affected plugin/package versions.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
plugins/revdiff-planning/scripts/launch-plan-review.sh	Detect cmux sessions via Ghostty env and route to cmux CLI branch (with explicit error if cmux CLI missing).
plugins/codex/skills/revdiff/scripts/launch-revdiff.sh	Same cmux-vs-ghostty detection fix for the Codex launcher copy.
.claude-plugin/skills/revdiff/scripts/launch-revdiff.sh	Same cmux-vs-ghostty detection fix for the Claude plugin launcher copy.
app/plugin_exit_code_test.go	Adds coverage for cmux sessions exposing Ghostty env vars; expands cleaned env set accordingly.
README.md	Updates terminal detection/docs and sandbox note snippet key.
site/index.html	Updates terminal detection text for cmux and ghostty.
site/docs.html	Updates terminal detection table/priority explanation for cmux and ghostty.
plugins/revdiff-planning/README.md	Documents the updated cmux detection priority vs Ghostty.
plugins/codex/skills/revdiff/references/install.md	Documents the updated cmux detection priority vs Ghostty.
.claude-plugin/skills/revdiff/references/install.md	Documents the updated cmux detection priority vs Ghostty.
plugins/revdiff-planning/.claude-plugin/plugin.json	Version bump for revdiff-planning plugin.
.claude-plugin/plugin.json	Version bump for revdiff Claude plugin.
.claude-plugin/marketplace.json	Version bumps to match plugin.json updates.
package.json	Version bump for the Pi package.

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