Auto-mode server-classifier context now has a size budget with progressive truncation

The context sent to the server-side auto-mode classifier now has an enforced byte budget. When the context is too large, Claude Code progressively trims it: first prior-turn context, then Chrome tab data, then the git visibility cache/remotes, then git status porcelain output. If the static, non-trimmable portion alone exceeds the budget, it logs a warning and fires the tengu_auto_mode_context_static_over_budget telemetry event; if the context still exceeds a harder ceiling after trimming, it is withheld entirely instead of being sent oversized.