phsl / new-api

This commit introduces a unified, maintainable solution for all model-pricing filter buttons and removes redundant code.

Key points
• Added `usePricingFilterCounts` hook
  - Centralises filtering logic and returns:
    - `quotaTypeModels`, `endpointTypeModels`, `dynamicCategoryCounts`, `groupCountModels`
  - Keeps internal helpers private (removed public `modelsAfterCategory`).

• Updated components to consume the new hook
  - `PricingSidebar.jsx`
  - `FilterModalContent.jsx`

• Improved button UI/UX
  - `SelectableButtonGroup.jsx` now respects `item.disabled` and auto-disables when `tagCount === 0`.
  - `PricingGroups.jsx` counts models per group (after all other filters) and disables groups with zero matches.
  - `PricingEndpointTypes.jsx` enumerates all endpoint types, computes filtered counts, and disables entries with zero matches.

• Removed obsolete / duplicate calculations and comments to keep components lean.

The result is consistent, real-time tag counts across all filter groups, automatic disabling of unavailable options, and a single source of truth for filter computations, making future extensions straightforward.