docs(fase-5): plan mobile UX rewrite ("Monolith Editorial")

- Add plan/fase-5-mobile-ux.md with 7-chunk breakdown:
    5.0 mobile tests (Playwright mobile-shell/masthead/swipe-delete + Vitest helpers)
    5.1 responsive shell (MobileTopBar + BottomTabBar + MobileDrawer)
    5.2 ScreenMasthead + px-4/md:px-6 pass
    5.3 /lists mobile cards
    5.4 /lists/[id] rows + red-zone swipe-delete
    5.5 undoQueue store + UndoToast
    5.6 scrollable frequency chips
    5.7 tasks/notes/search shell + masthead
    5.Z verify 211 + new M-series green
- Explicit gap analysis vs. current app + deliberate exclusions
    (no priority badges, no voice search, no fake meta like "Dairy · Weekly")
- Index design/ directory: Stitch mockups per screen (mobile + desktop variants),
  plus the "Monolith Editorial" DESIGN.md directing tonal shifts, masthead
  typography, glassmorphism, and the no-line rule
- Relocate DESIGN.md under design/slate_collective/DESIGN.md (old entry point) —
  the current design direction lives at design/DESIGN.md
- Reference design/ from CLAUDE.md + add Fase 5 to README phase index

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

README.md

@@ -15,6 +15,7 @@
 | Fase 2b — Realtime y Modo Compra | ✅ Completa (presence bloqueado por bug upstream de `supabase/realtime`) |
 | Fase 3 — Tareas y Notas | ✅ Completa |
 | Fase 4 — Búsqueda y Pulido | 🟡 Búsqueda + RLS audit completos; PWA install/push/rate-limit/JWT rotation diferidos a sprint de deploy |
+| Fase 5 — Rediseño UX Mobile | ⏳ Plan propuesto ("Monolith Editorial") — pendiente de implementación |
 | Suite de tests (pgTAP + Vitest + Playwright) | ✅ 211 tests verdes (34 pgTAP + 140 integración + 6 unit + 31 E2E), ejecutables con `just test-all` |
 
 ---
@@ -39,8 +40,11 @@ Las fases ya cerradas (0, 1, 2a) reflejan este patrón retroactivamente: la secc
 | Fase 2b | [fase-2b-realtime-modo-compra.md](plan/fase-2b-realtime-modo-compra.md) | 2–3 semanas |
 | Fase 3 | [fase-3-tareas-notas.md](plan/fase-3-tareas-notas.md) | 1–2 semanas |
 | Fase 4 | [fase-4-busqueda-pulido.md](plan/fase-4-busqueda-pulido.md) | 1 semana |
+| Fase 5 | [fase-5-mobile-ux.md](plan/fase-5-mobile-ux.md) | 1–2 semanas |
 
-**Total estimado: 9–13 semanas**
+**Total estimado: 10–15 semanas (con Fase 5 mobile)**
+
+Los mockups de referencia viven en [`design/`](design/) (organizados por pantalla — ver `design/DESIGN.md` para la dirección "Monolith Editorial").
 
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