Split kit and keys; KEYS GEN with MOTIF, 303, TURING, ARP

- genome(seed, salts) now has three parts with their own RNG streams:
  shared (steps, form, swing, arc, layback, fill odds, phase offset),
  kit (density, frame, accent cycle, free snare) and keys (scale/root,
  progression, motif, hocket, bass tone, note lengths, range). ROLL KEYS
  now renews the harmony too; ROLL KIT leaves the keys alone.
- Keys generators share one signature and can fix note lengths:
  MOTIF (the old line), 303 (acid bass, answers in the rests, drone or
  silent pad), TURING (8/16-bit shift register, DRIFT flips bits, 16-bar
  window), ARP (triad/7th arpeggio, roots on kicks).
- Pages: KIT GEN, KEYS GEN; ROLL shows KIT / KEYS; slots keep both gens.
- Flash record v3 (old settings ignored). Bring-up golden checksums updated.
- C port matches; host test and ASan/UBSan pass.

Intended music change: every seed sounds different (genome split, new
generators). Vectors regenerated with npm run vectors; the case grid now
crosses all kit and keys generators, with TURING runs past its window.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/cases.js

@@ -1,21 +1,28 @@
-/* The golden-vector case list. Shared by gen-vectors.js and check-vectors.js. */
-var SEEDS=[0x5EEDB0C5,0x00000001,0xDEADBEEF,0x12345678,0xC0FFEE00,0x0BADF00D];
-var SETS=[[64,32],[0,0],[127,0],[127,127],[100,90],[40,64]];   // [energy, drift]
+/* The golden-vector case list. Shared by gen-vectors.js and check-vectors.js.
+   keys = KEYS GEN (0 MOTIF, 1 303, 2 TURING, 3 ARP); scale/root -1 = AUTO; bars (optional) overrides BARS. */
+var SEEDS=[0x5EEDB0C5,0x00000001,0xDEADBEEF,0x00009AAB];   // bars of 14, 16, 12 and 20 steps
+var SETS=[[64,32],[0,0],[127,127]];   // [energy, drift]
 var BARS=8;
+function base(seed,gen,keys,e,d){ return {seed:seed,salts:[0,0],gen:gen,keys:keys,energy:e,drift:d,fillBars:[],scale:-1,root:-1}; }
 function cases(){
   var out=[];
-  SEEDS.forEach(function(seed){ for(var gen=0;gen<5;gen++) SETS.forEach(function(ed){
-    out.push({seed:seed,salts:[0,0],gen:gen,energy:ed[0],drift:ed[1],fillBars:[],scale:-1,root:-1});
+  // every kit generator against every keys generator
+  SEEDS.forEach(function(seed){ for(var gen=0;gen<5;gen++) for(var keys=0;keys<4;keys++) SETS.forEach(function(ed){
+    out.push(base(seed,gen,keys,ed[0],ed[1]));
   }); });
-  // salts (re-rolling one half of the seed) and FILL
-  [0,2,4].forEach(function(gen){
-    out.push({seed:0x5EEDB0C5,salts:[3,0],gen:gen,energy:64,drift:32,fillBars:[],scale:-1,root:-1});
-    out.push({seed:0x5EEDB0C5,salts:[0,5],gen:gen,energy:64,drift:32,fillBars:[],scale:-1,root:-1});
-    out.push({seed:0x5EEDB0C5,salts:[0,0],gen:gen,energy:80,drift:50,fillBars:[3,7],scale:-1,root:-1});
-  });
-  // ROOT / SCALE pages: [seed, gen, scale, root]; -1 = AUTO. Covers 5-, 6-, 7- and 8-note scales and each override alone.
-  [[0x5EEDB0C5,0,14,2],[0x5EEDB0C5,2,19,9],[0x5EEDB0C5,4,0,7],[0xDEADBEEF,1,18,-1],[0x12345678,3,-1,5],[0xC0FFEE00,0,7,11],[0x00000001,1,20,0]].forEach(function(k){
-    out.push({seed:k[0],salts:[0,0],gen:k[1],energy:64,drift:32,fillBars:[3],scale:k[2],root:k[3]});
+  // ROLL (salts) and FILL, per keys generator
+  for(var keys=0;keys<4;keys++){
+    var a=base(0x5EEDB0C5,0,keys,64,32); a.salts=[3,0]; out.push(a);
+    var b=base(0x5EEDB0C5,2,keys,64,32); b.salts=[0,5]; out.push(b);
+    var c=base(0x5EEDB0C5,keys===3?4:1,keys,80,50); c.fillBars=[3,7]; out.push(c);
+  }
+  // TURING over more than its 16-bar window: locked at drift 0, flipping at drift 64 and 127
+  [0,64,127].forEach(function(d){ var t=base(0x12345678,1,2,64,d); t.bars=24; out.push(t); });
+  // a long 303 and ARP run for the phrase variants
+  [1,3].forEach(function(keys){ var t=base(0xC0FFEE00,0,keys,90,100); t.bars=16; out.push(t); });
+  // ROOT / SCALE pages: [seed, gen, keys, scale, root]. Covers 5-, 6-, 7- and 8-note scales and each override alone.
+  [[0x5EEDB0C5,0,0,14,2],[0x5EEDB0C5,2,3,19,9],[0x5EEDB0C5,4,1,0,7],[0xDEADBEEF,1,2,18,-1],[0x12345678,3,0,-1,5],[0xC0FFEE00,0,1,7,11],[0x00000001,1,3,20,0]].forEach(function(k){
+    var c=base(k[0],k[1],k[2],64,32); c.fillBars=[3]; c.scale=k[3]; c.root=k[4]; out.push(c);
   });
   return out;
 }