kb: add blues guitar pack

5 forms (standard/quick-change 12-bar, 8-bar, minor blues, turnaround
cycle) x 2 plays each: barre shuffle, Texas 9th stabs, Chicago tritone
shells, minor m7 + 7#9 climax. 4 named comping patterns, improv rules,
2 sourced licks. Validator and build green.

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

src/data/kb/blues/meta.js

@@ -0,0 +1,7 @@
+export default {
+  id: 'blues',
+  label: 'Blues',
+  feel: 'shuffle',
+  tempoRange: [60, 180],
+  character: 'Dominant 7ths on every chord, swung eighths or 12/8 triplets, and the ♭3-against-3 tension that makes it talk — form is sacred, everything else is conversation.',
+}