JV‑880 dance loops run at wrong tempo; PCM oversampling + reg_slots hardcoded #7

Hi! I’ve been porting this JV880 emulation to Ableton Move (https://github.com/charlesvestal/move-anything-jv880) and noticed phrase‑loop patches (e.g., SR‑JV80‑06 Dance “Dance Again” / “Easy R&B”) run too fast.

It looks like mini‑jv880 has two PCM timing differences vs jv880_juce:

• reg_slots is hard‑coded to 28.
• oversampling is forced off.

jv880_juce uses reg_slots = (config_reg_3d & 31) + 1 and forces oversampling on; applying that fixed the loop tempo for me.

Proposed change (in src/emulator/pcm.cpp):

 -    constexpr int reg_slots = 28;
 +    int reg_slots = (pcm.config_reg_3d & 31) + 1;

 -            if (false) // oversampling
 +            if (true) // oversampling

 -        constexpr int cycles = (reg_slots + 1) * 25;
 +        const int cycles = (reg_slots + 1) * 25;

This matches jv880_juce behavior and fixes the tempo issue on the SR‑JV80‑06 Dance expansion for me. Not sure if oversampling was disabled for performance; sharing in case it helps.