docs: add Storybook section to FRONTEND-TOOLING.md

dev-docs/FRONTEND-TOOLING.md

@@ -65,3 +65,32 @@ backstop.
 Runs against `apps/portal/`. `apps/app/` has no test suite yet —
 build + typecheck are its only automated gates. Bringing Vitest
 coverage to `apps/app` is a separate backlog item.
+
+## Storybook
+
+Storybook 10.x is installed in apps/app/ as a component development
+and documentation tool.
+
+**Scripts (run from apps/app/):**
+- `pnpm storybook` — dev server on http://localhost:6006
+- `pnpm build-storybook` — static build to storybook-static/
+
+**Config files:**
+- apps/app/.storybook/main.ts — framework, stories glob, addons, viteFinal aliases
+- apps/app/.storybook/preview.ts — PrimeVue (via installPrimeVue plugin), Tailwind
+
+**Stories location:** co-located with components (ComponentName.stories.ts
+next to ComponentName.vue). Exception: smoke-test stories live in
+src/stories/.
+
+**Addons (explicit, no addon-essentials):**
+- @storybook/addon-docs — autodocs, prop tables
+- @storybook/addon-a11y — axe-core accessibility checks per story
+
+**Scope boundary:** Storybook = isolated render, autodocs, a11y.
+Interaction testing (click, form submit, emit) stays in Playwright CT.
+Do NOT install @storybook/addon-interactions.
+
+**Not in Storybook:** page-level views, components with direct
+useAuthStore / useOrganisationStore calls (these need to be
+decoupled to props first).