Kaia Counter v0.5.4 — SUCCESS display

Success state:
- SUCCESS: small, subdued status text.
- GOT IT!: larger, bold completion text.
- No disabled grey button remains in the success display.
- Cooldown logic remains unchanged.
- When cooldown expires, GET NUMBER returns.
- Existing counter/history is preserved.
- Plugin identity preserved: kaia-counter-test/kaia-counter-test.php
