feat : persist ForgeMode soundscape volume to localStorage

[tmdeveloper007]

Closes #1885

Summary of What Has Been Done

Added localStorage persistence for the ForgeMode soundscape volume preference.

Changes Made

• Modified the volume state initialization to read from localStorage.getItem("forgeMode_volume") if a saved value exists, defaulting to 0.5
• Added a useEffect that writes the volume value to localStorage.setItem("forgeMode_volume", volume) whenever the volume state changes

Impact it Made

• Users no longer need to adjust their preferred volume every time they enter ForgeMode
• Better UX continuity across page navigation and browser sessions
• Minor but meaningful quality-of-life improvement for frequent ForgeMode users

Note: Please assign this PR to the tmdeveloper007 account.