Hold Note Part 1

Add this game-feel effect to my 2D game: Hold Note — Sustain Sparks.

Reference scene (context only — map it onto my own characters and sizes):
A rhythm game note lane with hold (long) notes, seen flat from the side. Art is pixel art; all sizes are screen pixels — scale them to your own lane. Times are seconds, t = 0 is the moment a hold is released (exactly on the beat; the music is 120 BPM). The stage is dark warm brown #1a1210. A horizontal lane 60px tall (#2a1d16, with 6px #5a3a2a rails above and below) runs across the screen; faint gold vertical beat lines (3px, 12% opacity) are drawn every 75px and scroll with the notes. The hit marker sits near the left end: a 60×60px square outline, 6px thick, cream #fff6d8 at 75% opacity, with a 12% cream fill inside. Every note is a hold note: a head plus a tail 150px long (one second at the scroll speed of 150px/s). The heads come in 5 kinds that differ in color and shape, all 8×8 art pixels drawn at 7px (56px) with a dark #1a1014 outline: a gold #FFC24B diamond, a mint #5BE3B0 circle, an orange #ff9f43 square with a dark center dot, a silver #d8e2ea left-pointing arrow, and a pink #ff5a7a heart (7×7 at 8px). They repeat in a fixed 12-note pattern (diamond, circle, square, arrow, heart, circle, diamond, square, heart, arrow, circle, square). The tail is a 24px bar in the head's color (a darker 6px strip along the bottom, a light 3px highlight near the top, a 3px dark outline) and ends in a light 3px end cap. Holds come back to back: when one tail end reaches the marker the player releases (t = 0), and 0.08s later (12px) the next head reaches the marker and the next hold starts, so a hold is running almost all the time. While a note is held, its head stays pinned on the marker and the tail is eaten into the marker as it scrolls. On release, the old head flashes white, grows slightly and disappears within 0.08s. The judgment for each release is PERFECT (gold #FFC24B) or GREAT (mint #5BE3B0). Along the bottom, 18 small equalizer bars (15px wide, 6–28px tall, mint or gold at about 22% opacity) jump every half beat.

The effect:
While a hold is held, spawn 40 sparks per second at the top of the marker (12px above the lane center). Each spark lives 0.45s: launch angle straight up ±37° (random per spark), speed 200–340px/s, gravity 260px/s² pulling down. Size steps down from 12px to 9px (after 35% of its life) to 6px (after 70%); …

The rest of this prompt — exact sizes, easing, colors and particle counts — and full prompts 2–6 are in the pack.