Test build 26: 2.5-b26 — every DX7 voice as loud as SLOOP's own sounds

Every DX7 voice plays as loud as SLOOP's own sounds. SLOOP levels its 153 sounds by measuring each on a computer (tools/level_presets.py); a DX7 voice used to take FM6's first sound's trim and play as loud as its patch happened to be — the FM-1's factory voices up to 18 dB apart. Now the FM-1's 128 factory voices and the deckard vocal voices are measured the same way (tools/level_dx.py, the same phrases, loudness and target) and listed in the firmware by the sound of each: within 1 dB, 0.23 dB rms. Any other voice gets an estimate from its envelopes, about 3 dB rms. Very quiet voices stop at the +11.5 dB ceiling SLOOP's own quietest sounds share (19 factory ones, mostly percussion, 1–8 dB short). The trim follows the voice: a pick, PTCH, a project, a user preset.

Also in 25: every DX7 voice in banks 5–12 shows its own name.

Safe over builds 19–25: nothing is erased, no bank needs reloading. Going to plain upstream and back can erase banks 1–8 — save a backup in the editor first. Not a SLOOP release.