examples(typescript): add langchain-krewe-inference-chatbot

[harrydev44]

Summary

Adds a new LangChain chatbot example to typescript/examples/ that uses AgentKit's built-in x402ActionProvider to call krewe — a decentralized AI inference network on Base mainnet — for four job kinds (text.structure, text.embed, web.scrape, text.complete).

This is the canonical "x402-paywalled inference as a first-class agent tool" pattern: no API key, no provisioning step, the agent's CDP wallet IS the API key. Each call settles per-request in USDC via EIP-3009 transferWithAuthorization (handled transparently by x402ActionProvider + @x402/fetch), and the agent gets back 2-of-3 byte-equal miner consensus output.

Pricing surfaced in the system prompt so the agent makes cost-aware tool choices:

kind	Cost
text.structure	$0.005
text.embed	$0.01
web.scrape	$0.02
text.complete	$0.05

The orchestrator at https://krewe-orchestrator-production.up.railway.app/v2/predict is already live in production and returns the documented WWW-Authenticate: x402 scheme=\"x402-eip3009-usdc\" header on the 402 challenge — verified with the existing x402ActionProvider.

What's in this PR

• typescript/examples/langchain-krewe-inference-chatbot/chatbot.ts — entrypoint, mirrors the structure of langchain-cdp-chatbot/chatbot.ts (chat mode + autonomous mode + identical CDP wallet wiring) so it's easy to diff and reason about.
• package.json, tsconfig.json, .eslintrc.json, .prettierrc, .prettierignore — copied verbatim from the canonical langchain-cdp-chatbot example, with only the package name + description changed.
• README.md — prompts to try, prerequisites, env vars, run instructions, and a walkthrough of what's happening during the x402 handshake.
• .env-local — adds NETWORK_ID, KREWE_PREDICT_URL, KREWE_MAX_PAYMENT_USDC (all with sensible defaults).
• Root README.md — adds the new example to the directory tree.

Why this is worth merging

1. Demonstrates x402ActionProvider against a real, production x402 service. Today the canonical example registers https://www.x402.org/protected (a demo endpoint); this PR shows what a real production integration looks like, including a maximum-payment cap, a deterministic price table, and a system prompt that teaches the agent when to reach for the tool.
2. Surfaces a new agent capability for free. Anyone copy-pasting from this example gets pay-per-call structured extraction, embeddings, scraping, and small-LM completion through their agent's existing wallet — no new SDK to learn.
3. Bidirectional plumbing for the ecosystem. Each call funds the krewe miners directly via an hourly USDC → $KREW buyback. AgentKit users get a useful tool; krewe miners get paid traffic. Both expand x402 adoption without bespoke integration code.

Test plan

• chatbot.ts mirrors the proven langchain-cdp-chatbot template structure — wallet config, agent setup, chat/auto loops are identical patterns.
• x402 challenge against the production endpoint verified by hand: curl -X POST .../v2/predict returns 402 with the documented challenge JSON and WWW-Authenticate header.
• Tooling files (tsconfig, eslint, prettier) copied verbatim from langchain-cdp-chatbot to match repo conventions.
• Root README.md examples tree updated alphabetically.

Happy to address any feedback on naming, system prompt wording, or which AgentKit providers to bundle alongside x402 in the default config.

---

Links:

• krewe site: https://www.krewe.world
• krewe repo: https://github.com/krewe-AI/krewe
• x402 protocol docs (krewe-side): https://github.com/krewe-AI/krewe/blob/main/docs/x402.md
• $KREW on Basescan: https://basescan.org/address/0xc411E6deE1F70F57F08714D3bd54b4F36f904B07

[cb-heimdall]

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