feat: add Requesty provider

[Thibaultjaigu]

Summary

Adds Requesty as a dedicated provider, mirroring the existing openrouter provider.

Requesty (https://requesty.ai, https://docs.requesty.ai) is an OpenAI-compatible LLM router. Like OpenRouter it uses provider/model naming (e.g. openai/gpt-4o-mini, anthropic/claude-sonnet-4-5) and a single chat completions endpoint.

Changes

• src/providers/requesty/api.ts - base URL https://router.requesty.ai/v1 (base https://router.requesty.ai + /v1/chat/completions endpoint), Authorization: Bearer <apiKey>, and optional HTTP-Referer / X-Title analytics headers (same header names OpenRouter uses).
• src/providers/requesty/chatComplete.ts - request config and response/stream transforms mirroring the OpenRouter provider, including reasoning and usage handling. OpenRouter-specific request params that Requesty does not use (transforms, provider, models) and the OpenRouter-only OPENROUTER PROCESSING stream keepalive branch are omitted. Default model is openai/gpt-4o-mini.
• src/providers/requesty/utils.ts - transformReasoningParams / transformUsageOptions helpers mirroring OpenRouter.
• src/providers/requesty/index.ts - provider config wiring.
• src/providers/index.ts - registers requesty in the provider map.
• src/globals.ts - adds the REQUESTY constant and its VALID_PROVIDERS entry.
• src/data/providers.json - adds the Requesty provider entry.

Testing

• tsc --noEmit: no new type errors introduced by these files (only the two pre-existing errors in bytez and open-ai-base remain).
• jest src/: 47 tests pass, same as on a clean checkout (the failing suites are pre-existing and caused by missing .creds.json / an absent hooksService module, unrelated to this change).
• prettier --check passes on all edited files.
• Live check against the Requesty endpoint (POST https://router.requesty.ai/v1/chat/completions, model openai/gpt-4o-mini) confirms the base URL, Bearer auth, and provider/model naming work end to end.

Reference: https://app.requesty.ai/router/list , keys at https://app.requesty.ai/api-keys

I work at Requesty. This mirrors the existing OpenRouter provider as closely as possible. Happy to adjust or close it if it's not a fit.