Convert MiniMessage hex colors to legacy ampersand format before translation

[Chwitst187]

Motivation

• messages.yml uses MiniMessage-style hex tags like <#RRGGBB> while downstream color formatters only handle legacy & codes, causing hex tags to be shown literally instead of colored.
• Convert MiniMessage hex tags to the legacy ampersand hex form so existing formatters can render the intended colors without a larger refactor to MiniMessage/adventure everywhere.

Description

• Added a MINI_HEX_PATTERN regex and a helper convertMiniMessageHexToLegacyAmpersand(String) that converts <#RRGGBB> into &x&R&R&G&G&B&B sequences.
• Updated formatMessage(...) to run the conversion before calling colorFormatter.translateAlternateColorCodes('&', ...) so formatted messages render hex colors correctly.
• Updated prefix(...) to apply the same conversion for consistent prefix rendering; changes are in plugman-core/src/main/java/core/com/rylinaux/plugman/file/messaging/MessageFormatter.java and include an import for java.util.regex.Pattern.

Testing

• Attempted to run mvn -q -pl plugman-core,plugman-bukkit -am test -DskipTests, but the Maven run failed due to external repository resolution returning HTTP 403 from https://repo.maven.apache.org/maven2, so automated tests could not be executed in this environment.
• No automated test failures in-project were observed because tests could not be fetched/run due to the network/repository error.

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Codex Task