feat(kb): blues piano cell — 5 progressions x 2 authored plays (task P-31)

Guide-tone/tritone dyad system with the parallel half- and whole-step
laws, 7#9 as the codified blue note, the bVI7->V7 five-voice plane,
VI7b9 turnaround hinge, RH sixths; solo two-fisted vs rootless-band
contrasts per play. KB now 164 plays. Critic returned once (turnaround
jump-kicks bars 3-4 dyad orientations flipped + 2 prose rewordings),
fixed, PASS on scoped re-gate (stepwise lap chain recomputed from
scratch; "only leap" now provably unavoidable, not just chosen).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/data/kb/index.js

@@ -7,6 +7,7 @@ import jazzPiano from './jazz/piano.js'
 import bluesMeta from './blues/meta.js'
 import bluesProgressions from './blues/progressions.js'
 import bluesGuitar from './blues/guitar.js'
+import bluesPiano from './blues/piano.js'
 import rockMeta from './rock/meta.js'
 import rockProgressions from './rock/progressions.js'
 import rockGuitar from './rock/guitar.js'
@@ -43,7 +44,7 @@ export default {
   blues: {
     meta: bluesMeta,
     progressions: bluesProgressions,
-    instruments: { guitar: bluesGuitar },
+    instruments: { guitar: bluesGuitar, piano: bluesPiano },
   },
   rock: {
     meta: rockMeta,