Redesign the setup flow and consolidate the CSS into one primitives layer

Onboarding asks explicitly for one or two parents and shows one card per
parent for balances; the balance form is per parent with inline
validation; the partner can be filled from the FK deduction or added
from it. Settings and Dashboard reuse the same form.

CSS: bare buttons carry no colour any more; buttons, cards, choice
cards, fields, alerts, badges, eyebrow and modal chrome are defined once
in primitives.css. Media queries live only in responsive.css. A style
guard test blocks hex, !important and stray media queries. Bilingual
fixes: calendar selects size by content, header no longer wraps. Vitest
is capped at four workers.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

frontend/src/hooks/useDayOverrides.ts

@@ -1,6 +1,7 @@
 import { useCallback, useEffect, useState } from 'react'
 import * as api from '@/services/api'
 import { useLatestRequest } from './useLatestRequest'
+import { useWorkspace } from '@/context'
 import type { DayOverride, DayOverrideCreateRequest } from '@/types'
 
 interface UseDayOverridesResult {
@@ -16,6 +17,7 @@ export function useDayOverrides(workspaceId: string): UseDayOverridesResult {
   const [isLoading, setIsLoading] = useState(false)
   const [error, setError] = useState<string | null>(null)
   const { start, isCurrent } = useLatestRequest()
+  const { bumpPlanVersion } = useWorkspace()
 
   const fetch = useCallback(async () => {
     const requestId = start()
@@ -42,16 +44,22 @@ export function useDayOverrides(workspaceId: string): UseDayOverridesResult {
     async (req: DayOverrideCreateRequest) => {
       await api.upsertDayOverride(req)
       await fetch()
+      // An override changes which days count as free/working, which feeds
+      // the at-risk-days analytics — bump the shared invalidation counter
+      // so other hook instances (e.g. useAnalytics) refetch. See
+      // `WorkspaceContext.planVersion`.
+      bumpPlanVersion()
     },
-    [fetch],
+    [fetch, bumpPlanVersion],
   )
 
   const remove = useCallback(
     async (id: string) => {
       await api.deleteDayOverride(id)
       await fetch()
+      bumpPlanVersion()
     },
-    [fetch],
+    [fetch, bumpPlanVersion],
   )
 
   return { data, isLoading, error, upsert, remove }