fix: Replace welcome text to use fmt-style placeholders

[sogladev]

Changes Proposed:

May fix runtime issues when using special characters like Lok’tar ogar in welcome text.

Replaces angle bracket placeholders in guild welcome messages with curly braces and updates substitution logic to use fmt for safer, clearer formatting.
Improves flexibility and reduces risks from manual string replacement.

Issues Addressed:

• Closes

Crash on my local setup for only Horde characters on line:

welcome_text = std::regex_replace(welcome_text, std::regex("<GUILD>"), player->GetGuildName());

with vars
m_name "Guardians of Honor"
welcome_text "Lok’tar ogar! Welcome to the horde starter guild <GUILD> <PLAYER>."

SOURCE:

Tests Performed:

How to Test the Changes: