Build 0.7.6: Operational Soundscape & Melee Doctrine Update

[NEW FEATURE: INTEGRATED TACTICAL AUDIO SYSTEM]● Open Sound Architecture: the engine now supports full user-defined audio ingestion. Commanders can assign custom MP3, WAV, or OGG files for melee, ranged, and ambient tracks.
● Proximity-Dynamic Volume: melee and ranged sfx now react independently to screen-center proximity and camera zoom, so nearby combat naturally stands out over distant engagements.
● Acoustic Clarity Protocol: integrated a 120ms silence window with organic randomization to eliminate metallic echoes and ensure a natural combat rhythm.
● Quad-State Operation Toggle: new master control to cycle between 'Total Off', 'Simulation Only', 'Battle Only', and 'Dual Mode'.
● Cinematic Music Engine: persistent background tracks with manual calibration and full synchronization with the 'Reset' (Z) command.[NEW FEATURE: MELEE DOCTRINE CALIBRATION]● Melee Without Ammo Permission: troops can now be configured to maintain lethality in close combat even after completely depleting their discharge ammunition.
● Resource Conservation Logic: automatically prevents ammo consumption during active duel sequences, simulating bayonet charges and hand-to-hand drills.
● Conditional UI Sync: the melee toggle automatically activates and deactivates based on the master ammo system state to prevent configuration errors.