feat(kb): schema + validator + smoke for progression levels and licks (task C-20)

Optional additive shapes: progression level (foundation|intermediate)
and per-pack licks (8-word technique vocab, tab notes string 1-6 /
fret 0-15, ids global with progressions). Validator exports checkLick
as a lib for smoke (KB_VALIDATE_AS_LIB guard); smoke 776 -> 787.
Critic PASS (independent sabotage re-proof: injected bad lick exit 1
with named errors; weakened vocab fails smoke 2/787).

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

src/data/kb/SCHEMA.md

@@ -46,12 +46,20 @@ export default [
     mode: 'major',               // major | minor | dorian | mixolydian | …
     songs: ['Autumn Leaves'],
     tip: 'One transferable idea.',
+    level: 'intermediate',       // OPTIONAL: 'foundation' | 'intermediate'
   },
 ]
 ```
 
 4–8 progressions per style. Cross-check `docs/progression-repertoire.md` §1.
 
+**`level` (optional).** Tags the progression's difficulty for the in-app level
+filter. Allowed values: `'foundation'` (the style's bread-and-butter loops) or
+`'intermediate'` (secondary dominants, chained ii–Vs, backdoor, borrowed
+chords…). **Omitting the field is fine and means `'foundation'`** — consumers
+treat an absent `level` as foundation, so existing styles need no edits. The
+validator only checks the value when the field is present.
+
 ## Instrument packs
 
 Common envelope:
@@ -126,6 +134,76 @@ Voicings are degree recipes resolved through the chord quality. Degrees: `'1' '3
 }
 ```
 
+## Licks (optional, guitar first)
+
+A style's instrument pack may also teach short, named licks — the ordered-note
+phrases the Licks & Techniques cards render. **The whole section is optional**:
+a pack without licks is complete and valid.
+
+**How to register licks:** add a `licks` array as one more top-level key on the
+instrument pack's default export (next to `styleIntro`/`comping`/`plays`/`improv`
+in e.g. `src/data/kb/blues/guitar.js`). No change to `src/data/kb/index.js` is
+needed — the registry already exposes the whole pack, and the UI reads
+`kb[style].instruments.guitar.licks ?? []`.
+
+```js
+export default {
+  styleIntro: '…',
+  comping: [ /* … */ ],
+  plays: { /* … */ },
+  improv: { /* … */ },
+
+  // OPTIONAL — structured licks (this section):
+  licks: [
+    {
+      id: 'blues-box1-bb-answer',   // '<style>-<slug>', globally unique
+                                    // (shares ONE id namespace with progression ids)
+      name: 'B.B. box answer phrase',
+      level: 'foundation',          // 'foundation' | 'intermediate' (required)
+      chordContext: 'over the I7',  // which chord/station it fits — free text,
+                                    // e.g. 'dom7' or 'over the V7 turnaround'
+      techniques: ['bend', 'vibrato'],  // summary tags, from the fixed vocabulary below
+      source: 'the B.B. King box, e.g. "The Thrill Is Gone" fills', // recommended attribution
+      tab: [                        // the ORDERED note sequence (played first → last)
+        { string: 2, fret: 8 },                        // string 1 = high e … 6 = low E
+        { string: 1, fret: 8, technique: 'bend' },     // fret 0 (open) … 15
+        { string: 1, fret: 10, technique: 'vibrato' }, // technique is optional per note
+        { string: 2, fret: 8 },
+      ],
+    },
+  ],
+}
+```
+
+Field rules (all enforced by `node scripts/validate-kb.mjs` when `licks` is present):
+
+| Field | Rule |
+|---|---|
+| `id` | starts with `'<style>-'`; globally unique across **all** progression and lick ids in the whole KB |
+| `name` | required, non-empty |
+| `level` | `'foundation'` or `'intermediate'` — nothing else |
+| `chordContext` | required, non-empty string — tells the player *where* the lick lands |
+| `techniques` | array; every entry from the fixed vocabulary below (empty array = plain-picked) |
+| `tab` | non-empty ordered array of `{string, fret, technique?}` |
+| `tab[].string` | integer 1–6 (**1 = high e, 6 = low E** — standard tab convention; note `rootStr` in shapes counts the same way) |
+| `tab[].fret` | integer 0–15 (0 = open string) |
+| `tab[].technique` | optional; from the vocabulary; must **also** appear in the lick's `techniques[]` summary so card tags stay honest |
+| `source` | optional but recommended — name where the lick comes from (checklist: nothing invented) |
+
+**Fixed technique vocabulary** (both for `techniques[]` and per-note `technique`
+— the validator rejects anything else):
+
+`hammer-on` · `pull-off` · `slide` · `bend` · `double-stop` · `ghost-note` · `chromatic-approach` · `vibrato`
+
+Like shapes, licks are **key-agnostic in spirit**: write them where they sit in
+the style's home position and say in `chordContext` which chord they fit; the
+tab renders as absolute string/fret positions.
+
+Note: the older freeform `improv.licks` (prose `{tab/notation, description,
+over, source}`) is unchanged and still welcome — it feeds the improv text
+section. This top-level `licks` array is the *structured* shape that the lick
+cards render and the validator checks.
+
 ## Musician checklist (self-review before committing)
 
 - [ ] Plays per progression genuinely differ in register/density/technique
@@ -133,4 +211,5 @@ Voicings are degree recipes resolved through the chord quality. Degrees: `'1' '3
 - [ ] The style is recognizable from the rhythm descriptions alone (bossa ≠ jazz with new labels)
 - [ ] Every tip teaches a transferable idea (voice leading, register, space), not just "play this"
 - [ ] Songs/licks have sources; nothing invented
+- [ ] Lick techniques use only the fixed vocabulary; every lick is playable as written (strings 1–6, frets 0–15, in order)
 - [ ] `node scripts/validate-kb.mjs` green; `npm run build` green