feat: Add BlockRun as AI provider with x402 micropayments

[1bcMax]

Summary

Adds BlockRun as a new AI provider option alongside OpenAI and Grok. BlockRun enables wallet-based pay-per-request AI access via x402 micropayments — no API keys required.

Key Benefits:

• No API key management: Users bring their own Base chain wallet
• Cost transparency: Pay exactly what you use with on-chain USDC micropayments
• Privacy/self-custody: Private keys never leave the user's machine
• Model variety: Access 20+ models including OpenAI, Anthropic Claude, xAI Grok, Google Gemini, DeepSeek

Changes

File	Description
_shared/ai/callBlockRun.ts	New BlockRun provider with x402 payment flow
_shared/ai/types.ts	BlockRun type definitions
event-analysis-agent/index.ts	BlockRun provider support
event-analysis-agent/types.ts	paymentCost metadata field
.env.example	BLOCKRUN_WALLET_KEY documentation

Usage

1. Set BLOCKRUN_WALLET_KEY environment variable (Base chain private key, 0x-prefixed)
2. Fund wallet with USDC on Base mainnet
3. Use models like blockrun/gpt-4o, blockrun/claude-sonnet-4, blockrun/grok-3

// Example: Use Claude via BlockRun
const response = await fetch(edgeFunctionUrl, {
  method: "POST",
  body: JSON.stringify({
    markets: [...],
    eventIdentifier: "BTC-PRICE",
    pmType: "Polymarket",
    model: "blockrun/claude-sonnet-4", // or blockrun/gpt-4o, blockrun/grok-3
  }),
});

Available BlockRun Models

Model	Provider
blockrun/gpt-4o, blockrun/gpt-4o-mini	OpenAI
blockrun/claude-sonnet-4, blockrun/claude-opus-4	Anthropic
blockrun/grok-3, blockrun/grok-3-mini	xAI
blockrun/gemini-2.5-pro, blockrun/gemini-2.5-flash	Google
blockrun/deepseek-chat, blockrun/deepseek-reasoner	DeepSeek

Test Plan

• Type checking passes (deno check)
• E2E test with GPT-4o-mini via x402 payment
• E2E test with Grok-3-mini via x402 payment
• Manual test in PredictOS UI with BlockRun model

Links

• BlockRun Documentation
• x402 Protocol Spec