Use compact PUP startup banner on Android

[mpfaffenberger]

Problem

[mpfaffenberger]

Scope expanded before the documentation change: update README's preferred released-package Android command to pipx run code-puppy, while retaining pipx install --editable . for source checkouts. Document the 14-day temporary environment cache without discouraging the preferred command.

[mpfaffenberger]

Fixed in commit $(git rev-parse --short HEAD). Android now passes PUP to the startup pyfiglet renderer while other platforms retain CODE PUPPY; README now prefers pipx run code-puppy for released Android usage. Focused CLI validation: 105 passed, Ruff clean.