[hemaprathaban]

Adds RainDragon as an inference provider, with mappings for Gemma 4 26B and Gemma 4 31B.

Public sources for the values in this PR:

• API base URL and sign-up: https://inference.raindragon.ai
• Pricing and context length: https://inference.raindragon.ai/v1/models (public, no login needed). Gemma 4 26B $0.075 in / $0.35 out per M tokens, Gemma 4 31B $0.13 / $0.38, cached input $0.03/M.
• Privacy policy: https://inference.raindragon.ai/privacy
• Region: inference runs in the US (us-east).
• Rate limits: not published, so set to null as the schema allows.

Happy to change anything you need.

[madeburo]

Thanks for adding RainDragon! Registry validation passes for all 544 files, and the model IDs, standard input/output prices, and provider-specific context windows match the public /v1/models response.

There are two discrepancies to resolve before merging:

1. Cached-input pricing for Gemma 4 26B — mappings/raindragon/gemma-4-26b.yaml sets cache_read_per_million: 0.02, but the public pricing API currently reports cached_input_price_per_million: 0.03 for google/gemma-4-26B-A4B-it. Please align the mapping with the public USD-per-million rate, or provide an authoritative source explaining when the $0.02 rate applies. The 31B cached-input price already matches.

2. Prompt/response retention — providers/raindragon.yaml describes prompts and responses as deleted after 24 hours, while the published privacy policy, particularly sections 1 and 4, says prompt/completion content is processed in memory and is not retained after request processing. Please clarify the applicable policy and make the registry description and public documentation consistent. This is a documentation discrepancy; I am not treating the public policy as independent verification of backend retention behavior.

Unknown rate limits being null are fine. I have not tested authenticated inference, so this review does not certify end-to-end API behavior. Happy to re-review once the two metadata discrepancies are resolved.