fix: restore fast human-readable Console pricing

[douglasmonsky]

Problem

Installed R7 Console inspection on merged 827be57 exposed three connected product regressions:

• /explore routes correctly but its default broad cost-aware share request took 33,006 ms on the maintained generation, despite the named top_threads MCP template completing its query in 22.827 ms.
• configured costs and estimated credits have 0% coverage because clean kernel installs have no rate-card.json; the product reset retired the old OpenAI documentation updater and bundled pricing assets while retaining only the rate-card calculator.
• major Console tables compress uncached input, cached input, reasoning, and output into one Token Mix cell instead of four sortable decision columns.

Required correction

• make Explore initial views use bounded persisted/named fast paths and prove warm installed browser latency;
• restore a maintained, source-stamped pricing bootstrap/update path using official OpenAI pricing provenance without hidden network work during reports;
• render the four token classes as separate sortable columns everywhere they are available, retaining compact responsive behavior without losing values;
• preserve explicit estimate/coverage labels, snapshot consistency, privacy, and exact selectors;
• cover clean install, absent/invalid/partial pricing, installed browser, deterministic assets, package data, and performance budgets.

This is an R7 blocking correction discovered through installed product qualification.