Initiële commit: VibeFinance 3-container opzet

Basislijn van de bestaande applicatie (Vite/React frontend, Express
backend, PostgreSQL) zoals die in de index stond, plus dev-, release-
en documentatiescripts.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/hooks/useTheme.js

@@ -0,0 +1,23 @@
+/**
+ * Geeft een thema-object (T) terug op basis van darkMode.
+ * Wordt gebruikt door alle componenten om consistent kleuren te krijgen.
+ */
+export function useTheme(darkMode) {
+  return {
+    // Exacte Finex kleuren (dark) / licht alternatief
+    bg:         darkMode ? "#241A39"                        : "#eef1f8",
+    card:       darkMode ? "rgba(22,23,27,0.30)"             : "#ffffff",
+    sidebar:    darkMode ? "#16171B"                        : "#f8faff",
+    border:     darkMode ? "rgba(139,92,246,0.15)"          : "rgba(0,0,0,0.07)",
+    muted:      darkMode ? "#8b8fa8"                        : "#94a3b8",
+    text:       darkMode ? "#ffffff"                        : "#0f172a",
+    subtext:    darkMode ? "#a0aec0"                        : "#64748b",
+    inputBg:    darkMode ? "rgba(139,92,246,0.08)"          : "#f1f5ff",
+    inputBorder:darkMode ? "rgba(139,92,246,0.2)"           : "#e2e8f0",
+    contentBg:  darkMode ? "#241A39"                        : "#eef1f8",
+    shadow:     darkMode ? "0 4px 24px rgba(124,58,237,0.25)"  : "0 4px 20px rgba(0,0,0,0.07)",
+    cardShadow: darkMode ? "0 4px 20px rgba(124,58,237,0.2)"  : "0 2px 8px rgba(0,0,0,0.06)",
+    radius:     "14px",
+    font:       "'Poppins', system-ui, sans-serif",
+  };
+}