v0.7.2: tighter rules on the board and in /pet

Tighter rules on the board and in /pet

• A creature is credited at most once a day, even when check-ins arrive at the same moment.
• One network can add two new creatures a minute (was five), and the board never takes more than 5,000 new creatures a day.
• The scanner accepts only whole flag names, and checks a --server address more strictly: https, or plain http only to this machine.
• /pet now passes only the 32-character code from an invite link to the command, and quotes a GitHub login and a self-hosted address.

The board changes are already live. To get the scanner and /pet changes: /plugin → Marketplaces → cclevel → Update marketplace, then /reload-plugins.