feat(gallery): add R05-R07 filter bank, chicken-head selector, round meter

Three more reference-batch widgets as inline SVG, from the Berna-style faceplate set:

- R05 filter slider bank: eight band faders with teal double-arrow caps on black tracks, frequency labels up top, a dB rail at the side. Per-band drag; the readout names the band and its attenuation.
- R06 chicken-head selector: the tapered lever aims at the engraved position (OFF/LO/MID/HI); the active legend lights. Click steps through.
- R07 round panel meter: porthole black bezel, cream dial, printed dB arc with red zone, drag-driven needle.

R07 shares the VU-law dB interpolation with R01 through a new vuDb helper, so the nonlinear scale lives in one place.

I verified all three in headless Chrome: band drags update cap and readout, the selector steps and relights, the meter needle tracks drags, no console exceptions. The gallery is at 60 cards.

0 files changed, 0 insertions, 0 deletions