docs(product): system-wide visual design language (S0-DS kit + S14 panel refresh)

LICE verified sufficient from vendored WDL — current editor draws at its
floor (flat fills, raw GDI text); no framework shift needed, D-A holds.
Adds design-language doc (palette, three directions, motion policy),
S0-DS shared drawing kit before S10, S14 panel refresh.

docs/product/midi-playback.md

@@ -743,6 +743,13 @@ Post-DAW-test directives (2026-07-26; see the "product name + UX overhaul" Adden
 8. **UX overhaul → "better than RS5K"** (**S10–S13**): direct-manipulation keyboard-strip
    keymap editor (S10), waveform + draggable loop points (S11), scale/ergonomics — scroll,
    search, direct numeric entry, ADSR (S12), and drop-to-load folding in the S8 relay (S13).
+9. **Visual design language → modern/sleek, system-wide** (**S0-DS** + **S14**): a shared
+   LICE drawing kit (gradients, AA, rounded controls, cached-font text, hover states — no new
+   toolkit; LICE is sufficient, D-A reinforced), sequenced **before** S10 so the keymap editor
+   is born in the new language; plus a lighter extension-side dock-panel refresh. Framing +
+   palette + three visual directions + toolkit/direction/scope forks:
+   `docs/product/visual-design-language.md`. Answers Daniel's "the VST is dogshit / temple os /
+   does Cockos have a toolkit" (2026-07-26, post-S1–S6 DAW test).
 
 **Authoritative from here:** **PLAN.md §Phase S** is the roadmap (S1–S6 the original
 dependency chain: spike → `Sample` fields → pure sampler core → Tier 0 → Tier 1 → embedded