The chat usage badge was hardcoded to ~8K-token Ollama defaults
(`CONTEXT_BUDGET_CHARS = 24_000`), which made every Fireworks session
look 150%+ full after a few hops even though models like Kimi-K2 carry
256K context windows. Now the budget is selected per-provider:
- Ollama → 24K chars (~8K tok), unchanged
- Fireworks → 384K chars (~128K tok), a safe floor for the smallest
Fireworks chat models (qwen2.5-coder 32K) while not stuffing the bar
for the larger ones
Auto-compact thresholds and the % badge both read this back from the
backend, so they now scale correctly when the user switches providers.