Add CLI demo GIF to README (Bounty #3)

[Asobu01]

Bounty Submission

Related Issue: #3

What I delivered

• Added a short terminal demo GIF under the CLI section in README
• Demo command shown exactly:
  npx x402charity donate testing-charity '$0.001' --network base-sepolia
• Included output with transaction hash

Acceptance Checklist

• GIF recorded and added to README
• Command matches requirement
• Transaction hash visible in output
• Duration kept under 15 seconds

Payout (Base USDC)

Wallet Address (Base): 0x8E906DB9131Df16F26c55e496f44Dec4D5cEd7c1

[vercel]

@Asobu01 is attempting to deploy a commit to the shawnpang's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Asobu01]

Second gentle follow-up on PR #11 for bounty #3. If any adjustment is needed for acceptance, I can update quickly. Thanks for taking a look when convenient.