New audio source type that filters a parent source to a specific frequency
band (bass 20-250Hz, mid 250-4kHz, treble 4k-20kHz, or custom range).
Supports chaining with frequency range intersection and cycle detection.
Band filtering applied in both CSS audio streams and test WebSocket.
Composite layers now support optional start/end LED range (toggleable)
and reverse flag, making composite a superset of mapped source. Layers
are collapsible with animated expand/collapse and consistent 0.85rem
font sizing. Delete button restyled as ghost icon button.
Also includes minor dashboard CSS overflow fixes.
Set WLED_RESTART=1 env var on tray restart so __main__.py skips
opening a new browser tab — the user already has one open.
Add important TODO item to eliminate WLED naming throughout the app
(package rename, i18n, build scripts, etc.).
