kb: add bossa nova guitar pack

5 progressions (Ipanema A-section, minor ii-V-i with m6 tonic, Blue
Bossa 16-bar, One Note Samba chromatic chain, Corcovado descent) x 2
plays on alternating root-string sets. Joao Gilberto rhythm layers
documented (thumb surdo + syncopated block, two-bar tied pattern,
partido alto contrast), improv map, sourced Ipanema melodic cell.
Validator caught 6 quality mismatches (6/9 grips on maj7/min7 steps)
- content fixed, gate untouched. Validator and build green.

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

src/data/kb/bossa/meta.js

@@ -0,0 +1,7 @@
+export default {
+  id: 'bossa',
+  label: 'Bossa Nova',
+  feel: 'bossa',
+  tempoRange: [110, 160],
+  character: 'A whole samba band condensed into one quiet guitar: metronomic thumb bass, syncopated chord block that never accents beat 3, and jazz harmony at conversation volume.',
+}