v2 : couche données complète + shell + primitives communes

- stores/collective.ts (état local-first, gabarits, import/export, seeds)
  + stores/decisions.ts (cycle de vie complet : capture→chemin→fenêtres→
  sessions→cristallisation→épreuve du réel→révocation)
- data/templates.ts : 7 gabarits (Page blanche observatoire-d'abord,
  5 points de départ, Institution symétrique)
- composables useFeed (13 sections du Fil en sélecteurs purs) + useSearch
  (index unique Cmd+K/Q0)
- shell : layouts default/bare, app.vue mince, useMood v2 (Source/Margelle/
  Nappe/Minuit), sceau 井 = logo, LdWorkspaceSelector avec finalité A1,
  LdAvatarStack (premier/second lieu), LdCountdown (suspension striée)
- 338 tests vitest verts, npm run build zéro erreur

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

frontend/app/engine/index.ts

@@ -1,11 +1,16 @@
 /**
- * Pure voting-formula engine — TypeScript port of backend/app/engine/.
- * Python is the reference implementation; the vitest suite in
- * frontend/tests/engine/ mirrors the backend pytest suite.
+ * Pure engine barrel — the SINGLE import surface of app/engine/.
+ *
+ * Re-exports EVERYTHING (functions, constants and types) from the eight
+ * pure modules. Stores and components import from '~/engine' (or relative
+ * '../engine') and never reach into individual files.
  */
 
-export { wotThreshold, smithThreshold, techcommThreshold } from './threshold'
-export { nuancedResult, LEVEL_LABELS, NUM_LEVELS } from './nuanced'
-export type { NuancedResult } from './nuanced'
-export { parseModeParams, formatModeParams } from './modeParams'
-export type { ModeParams } from './modeParams'
+export * from './threshold'
+export * from './nuanced'
+export * from './modeParams'
+export * from './parametric'
+export * from './settings'
+export * from './state'
+export * from './triage'
+export * from './impact'