kb: bootstrap foundation + jazz guitar gold standard

SCHEMA.md authoring contract, validate-kb.mjs quality gate (pitch-class
verification of shapes against chord qualities), registry, and the jazz
style: 5 progressions x 2 guitar plays (shells + drop-2), comping
rhythms, improv guidance, sourced licks. Validator and vite build green.

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

src/data/kb/jazz/meta.js

@@ -0,0 +1,7 @@
+export default {
+  id: 'jazz',
+  label: 'Jazz',
+  feel: 'swing',
+  tempoRange: [110, 230],
+  character: 'Harmony in constant motion — 7th chords everywhere, 3rds and 7ths doing the voice-leading work, rhythm section breathing around the soloist.',
+}