kb: add pop guitar pack (task P-02)

5 pop progressions x 2 plays: axis (I-V-vi-IV), '50s doo-wop, Canon pop line,
Mixolydian bVII, minor loop (i-bVI-bIII-bVII). Open campfire + movable/barre play each;
sus taught as fills (chords voiced plain). KB now 10 styles / 50 progressions / 100 plays.
Critic PASS (voicings hand-verified, no duplicate ids).

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

src/data/kb/index.js

@@ -27,6 +27,9 @@ import rnbGuitar from './rnb/guitar.js'
 import gospelMeta from './gospel/meta.js'
 import gospelProgressions from './gospel/progressions.js'
 import gospelGuitar from './gospel/guitar.js'
+import popMeta from './pop/meta.js'
+import popProgressions from './pop/progressions.js'
+import popGuitar from './pop/guitar.js'
 
 export default {
   jazz: {
@@ -74,4 +77,9 @@ export default {
     progressions: gospelProgressions,
     instruments: { guitar: gospelGuitar },
   },
+  pop: {
+    meta: popMeta,
+    progressions: popProgressions,
+    instruments: { guitar: popGuitar },
+  },
 }