feat: add Grooves app

[kosmar]

Summary

• Adds Grooves (app ID 30): a one-channel multi-genre MIDI drum helper with MPC-style feel, density fills and Any/Stacked jack modes.
• Seven drum voices (Kick, Snare, Hats, Open Hat, Low Tom, High Tom, Clap). Everything past Hats is optional and off by default, addressed through a packed channel map so the extra voices cost no extra params.
• Nine genres on a morph axis (Dub through Dubstep), scrubbed with Shift+fader and synced back to the Configurator Groove param.
• Eight drummer personas that transform the genre pattern after it is read, the way Bassment's bassist voices do: Elvin, Purdie, Clyde, Jaki, Sly, Allen, Pretty Tony and Dilla. Each profile carries shuffle, ghost density, backbeat lock, tom dispersal, clave rotation, roll rate, push or pull, limb drift and a machine amount. All of it is Feel scaled, so a flat Feel still plays the plain genre grid and the personas open up as Feel rises.
• Shift+tap plays a genre fill, Shift+hold escalates it into a solo.
• Manual entry with gesture and LED tables, including markdown table rendering so those tables display in the Configurator.

Note on the param ceiling

The app was already using all sixteen slots APP_MAX_PARAMS allows, so the separate Range param folds into the Jack enum, which now carries duty, stacked mode and range together. Stored blobs migrate on the value type at index 14, which preserves both the duty and the range the user had picked.

Gestures

Gesture	Action
Fader	Density
Shift + fader	Genre
Button + fader	Feel
Short press	Mute; unmuting also resets to the downbeat
Long press	Next drummer (LED flashes the persona colour)
Shift + tap	Genre fill until the next downbeat
Shift + hold	Solo

Test plan

• Flash firmware; load Grooves on a channel
• Kick, Snare and Hats fire in 4/4 with the selected Groove
• Fader raises density so extra hits fade in; Shift+fader scrubs the genre with the LED spectrum following
• Button+fader scrubs Feel; at Feel 0 the grid is flat and quantised
• Long press cycles the drummer and the button LED flashes a distinct colour per persona
• Personas are audibly distinct at high Feel: Purdie shuffles with ghosts, Jaki stays dead straight, Pretty Tony shifts the kick off the downbeat, Dilla drifts the hats against the kick
• Short press mutes; unmuting lands on the downbeat
• Shift+tap fills into the next bar; Shift+hold turns it into a solo
• Jack enum covers Any and Stacked in both ranges, plus CV In for Density, Feel and Reset
• A layout saved before this change still loads with its previous jack duty and range intact
• Configurator Manual for Grooves renders its tables correctly

Prerequisites

The platform pieces this app needs are under review as their own PRs, so that each app PR stays small enough to review on its own.

Required, since these APIs do not exist on current main:

• fix: keep the metronome off the clock pubsub #638 — tick counter plus App::clock_ticker
• feat: add non-blocking note and CC senders for voice engines #639 — non-blocking note and CC senders (try_send_*)
• feat: let apps write back their own params and notify the host #640 — ParamStore::update, so an app can write its own params back to the host
• feat: add shared app helper modules and libfp clock/brightness helpers #641 — shared genre_palette / groove / led_fx modules, plus the shared ornament module the personas build on

This branch currently carries its own inline copy of the code in #638, #639, #640 and #641. Once those land it will be rebased to drop the duplicates, which shrinks this diff to the app file plus its registry line.

Building any of this on a current Rust nightly also needs the toolchain fix in #632.

Note: ID 28 is reserved for Sift; Heat Pump holds 29 (#603). These PRs are independent from main.