Add QR code display on ppg serve startup

[2witstudios]

Epic 7: Polish & QA — Issue 2/6

Description

Print pairing QR code to terminal on server startup for easy iOS device pairing.

Acceptance Criteria

• Print token to stdout (shown once at generation time)
• QR code rendered to terminal using qrcode-terminal package
• Encode pairing URL: ppg://connect?host=...&port=...&ca=...&token=...
• Include CA fingerprint in URL for certificate pinning
• Only display QR when running in interactive terminal (not daemon mode)
• Add qrcode-terminal to package.json dependencies

Dependencies

• Requires: Create ppg serve command and Fastify server scaffold #63 (serve command), Implement TLS certificate generation #65 (TLS)

Files to Modify

• src/commands/serve.ts
• package.json (add qrcode-terminal)