fix(provider/moonshotai): align reasoning by model (#19582)

## Summary

- align `thinking` requests with the official K3, K2.7, K2.6, K2.5, and
Moonshot V1 model behaviors
- map generic reasoning controls only where the selected model supports
them
- preserve the deprecated `budgetTokens` option for compatibility while
warning and omitting the unsupported wire field
- update tests, type tests, documentation, examples, and release notes

## Verification

- `pnpm --filter @ai-sdk/moonshotai test:node` (95 tests)
- `pnpm --filter @ai-sdk/moonshotai test:edge` (95 tests)
- `pnpm --filter @ai-sdk/moonshotai type-check`
- `pnpm type-check:full`
- `pnpm check`

Fixes #19554