feat: add x402 bazaar + mcp examples

[CarsonRoscoe]

Summary

• Add Python Bazaar server example using the x402 Foundation SDK with the CDP Facilitator.
• Add Python MCP client and server examples using CDP-managed wallets for paid tools.
• Add a config-driven TypeScript Bazaar server with automatic discovery through createX402Server.
• Document setup, environment variables, and when to use Bazaar versus MCP examples.

Test plan

• Run Python Ruff formatting and lint checks.
• Verify the Python Bazaar server returns valid discovery metadata in its 402 response.
• Type-check and format the TypeScript Bazaar example.
• Run the MCP client/server flow end-to-end with funded CDP credentials.

Checklist

A couple of things to include in your PR for completeness:

• Updated the typescript README if relevant
• Updated the python README if relevant
• Added a changelog entry
• Added e2e tests if introducing new functionality

[cb-heimdall]

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