Make model pricing badges more granular (5-point Logarithmic Scale)

Right now, the 4 pricing buckets ($, $$, $$$, and red $$$) end up a bit too compressed because API pricing varies exponentially. For example, two models might both show as $$, but one is actually a fraction of the cost of the other.

Since keeping the simple green/red color scheme is great for UI cleanliness and avoids the contrast issues of yellow or orange, it would be awesome to just expand the scale to 5 states and map them logarithmically:

• $ (Green) — Ultra-economy

• $$ (Green) — Cheap

• $$$ (Green) — Mid-range

• $$$$ (Red) — Premium / Expensive

• $$$$$ (Red) — Ultra-expensive outliers

This keeps the clear mental model (Green = economy, Red = expensive warning) but gives enough granularity so models with vastly different prices (like Gemini Pro vs. GLM-5) don't get forced into the exact same bucket.