Terminal identity detection now feeds startup telemetry

What

• A new classifier reads the raw XTVERSION terminal-identification reply your terminal sends back and matches it against a list of known terminal apps (iTerm2, ghostty, WezTerm, tmux, kitty, and others) plus several version-format patterns.
• If the terminal isn't recognized, it's bucketed as "other"; if there's no reply at all, it's bucketed as "no_reply".
• The result is packaged as an xtversion field inside a tengu_terminal_probe telemetry event sent at startup.

Why This lets Claude Code understand which terminal emulators and versions people actually use, without sending raw, potentially inconsistent terminal strings — only normalized values reach telemetry.