Package-level declarations

Parses the CSS hex forms #RGB, #RGBA, #RRGGBB, #RRGGBBAA into an ARGB Int. The leading # is mandatory (matches what the native-rich-media preview renders); anything else — a bare hex string, a bad length, non-hex characters, empty or null — returns null so the strict parser can reject the whole config.

Decodes the native-config JSON into an InAppMessage, strictly to the typed contract.