Add Near Intents charge intent

[IkerAlus]

Summary

Adds the nearintents payment method implementing the existing charge intent. It settles one-time, cross-chain payments through the NEAR Intents 1Click Swap API: the client pays a source asset on any supported origin chain and the merchant receives an exact destination asset on any supported destination chain, with the NEAR Intents solver network executing the swap in between.

Notes for reviewers

• Push mode only (type="hash"): The source asset must be deposited before settlement, so there is no server-submitted/pull flow; the client always pays
  its own origin-chain network fee.
• Cross-chain field mapping: The standard amount/currency/recipient describe the client's origin-chain deposit, with recipient = the 1Click deposit address; the merchant's destination leg lives in methodDetails. This keeps push-mode verification ("confirm a transfer of amount currency to recipient") directly applicable.
• Challenge binding: 1Click issues a unique deposit address per quote, so recipient is challenge-specific and bound into the challenge id — a deposit
  cannot be replayed against a different challenge.
• Trust model: funds are held by the settlement backend during the swap, with an automatic refund to refundTo on any non-success terminal state.

Registers a new method against the already-standardized charge intent; it does not define a new intent.

Checklist

• make check passes
• make lint passes
• New method follows the method template, added under specs/methods/nearintents/
• References are stable (no hardcoded section pointers)

AI assistance

Drafting and formatting were done with AI assistance. All content has been reviewed by the author for RFC compliance and technical correctness.