CLI-028 — Add Full Stack App starter template

[dDevAhmed]

Summary

Add the MVP Full Stack App template with a clear frontend/backend/contracts separation appropriate for production-oriented Stellar development.

Scope

• controlled template files/metadata;
• generated frontend/backend/contracts structure;
• environment examples without secrets;
• setup/build smoke test;
• generated README.

Acceptance Criteria

• selectable through the controlled registry;
• generates successfully through CLI-026;
• generated project follows documented structure;
• no real credentials/secrets are included;
• smoke/setup validation is automated where practical.

Dependencies

• CLI-025
• CLI-026

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🏷 Labels

• type: feature
• area: templates
• priority: P1
• difficulty: advanced