feat(cli): add MPP and x402 fetch commands

[nkavian]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 78.27103% with 186 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
packages/core/src/flows/mpp-fetch.ts	57.46%	53 Missing and 4 partials ⚠️
packages/core/src/flows/x402-fetch.ts	58.99%	51 Missing and 6 partials ⚠️
packages/cli/src/commands/mpp/index.tsx	77.18%	33 Missing and 1 partial ⚠️
packages/cli/src/commands/x402/index.tsx	80.23%	33 Missing and 1 partial ⚠️
packages/cli/src/commands/payment-fetch.tsx	96.96%	2 Missing and 2 partials ⚠️

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