Furry Player

WIP

Runtime master key

• Runtime entrypoints now support FURRY_MASTER_KEY_HEX for injecting a 32-byte master key as 64 hex characters.
• If this variable is absent, the project still falls back to the built-in development key for compatibility.
• Setting FURRY_REQUIRE_MASTER_KEY=1 forces runtime entrypoints to reject the built-in fallback.
• Production deployments should always set FURRY_MASTER_KEY_HEX explicitly.