feat: add Prism Network action provider

[winterstacks]

What

Adds a prism action provider for renting real NVIDIA GPUs through Prism Network.

Five actions: wallet, list_gpus, lease_and_run, run, end_lease. An agent can price GPUs, rent one, run a command on it, and pay for it onchain in USDG, all in-loop.

The provider is self-contained and adds no new runtime dependencies (uses web3 and requests, already in the tree; SSH uses the standard library). It carries its own funded wallet via PRISM_AGENT_KEY and settles onchain in USDG, so it composes with any AgentKit wallet provider instead of spending the agent's primary wallet.

Testing

• ruff check and ruff format clean.
• pytest tests/action_providers/prism — 7 passing (mocked client).
• The read paths (wallet, list_gpus) were verified live against the Prism control plane; registration verified through from coinbase_agentkit import prism_action_provider.

Notes

• lease_and_run blocks while the machine provisions (usually one to four minutes) and spends real USDG, capped by max_usdg.
• Changelog fragment included.

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 1 Sum 2