feat(sprint-5): Phase 2 — React Query API client layer

- @tanstack/react-query with QueryClientProvider in providers/index.tsx
- Typed api-client.ts fetch wrapper with ApiError class + apiDownload
- Service modules: members, distributions, stock, reports, dashboard, portal, staff
- Offline banner component (onlineManager subscription)
- API error boundary with retry button
- Loading skeleton components (card, table, chart, form, dashboard)
- i18n for error/loading states (de/en)

cannamanage-frontend/pnpm-lock.yaml

@@ -53,6 +53,9 @@ importers:
       '@radix-ui/react-tooltip':
         specifier: 1.1.5
         version: 1.1.5(@types/react-dom@19.0.4(@types/react@19.0.12))(@types/react@19.0.12)(react-dom@19.1.3(react@19.1.3))(react@19.1.3)
+      '@tanstack/react-query':
+        specifier: ^5.101.0
+        version: 5.101.0(react@19.1.3)
       '@tanstack/react-table':
         specifier: ^8.21.3
         version: 8.21.3(react-dom@19.1.3(react@19.1.3))(react@19.1.3)
@@ -1642,6 +1645,14 @@ packages:
     peerDependencies:
       tailwindcss: '>=3.0.0 || insiders || >=4.0.0-alpha.20'
 
+  '@tanstack/query-core@5.101.0':
+    resolution: {integrity: sha512-cQetA74EB+seWySv1TTKr828TnP0u39m6LykwDXIo84SNortpDkp30TMEjkqtYCNP9c40uT/iwl6MLiufEt0Ow==}
+
+  '@tanstack/react-query@5.101.0':
+    resolution: {integrity: sha512-rLlJXSpkqfizLWgkR5+eLeIk0MvTx/meEIR7LRjxic+qxiQP8zVjq7BqQkiCMNLQBlLfuOLqqr6KO5GtrDlmSg==}
+    peerDependencies:
+      react: ^18 || ^19
+
   '@tanstack/react-table@8.21.3':
     resolution: {integrity: sha512-5nNMTSETP4ykGegmVkhjcS8tTLW6Vl4axfEGQN3v0zdHYbK4UfoqfPChclTrJ4EoK9QynqAu9oUf8VEmrpZ5Ww==}
     engines: {node: '>=12'}
@@ -4918,6 +4929,13 @@ snapshots:
       postcss-selector-parser: 6.0.10
       tailwindcss: 4.1.3
 
+  '@tanstack/query-core@5.101.0': {}
+
+  '@tanstack/react-query@5.101.0(react@19.1.3)':
+    dependencies:
+      '@tanstack/query-core': 5.101.0
+      react: 19.1.3
+
   '@tanstack/react-table@8.21.3(react-dom@19.1.3(react@19.1.3))(react@19.1.3)':
     dependencies:
       '@tanstack/table-core': 8.21.3