Separate JSON API backend (vm_api.py) + React+TanStack frontend scaffold

- vm_api.py: pure FastAPI JSON API on :8098 with CORS
- vm-api.service: systemd unit for API (replaces inline HTML vm_web.py for frontend)
- vm_web.py: kept intact as fallback; Apache now proxies /api/ -> :8098
- frontend/: Vite + React + TanStack Query scaffold
- Apache vhost updated: DocumentRoot -> frontend/dist, /api/ proxy, SPA fallback
- All original HTML pages still functional via :8099 during transition

frontend/node_modules/@tanstack/react-store/src/index.ts

@@ -0,0 +1,61 @@
+export * from '@tanstack/store'
+
+export { useStore } from './useStore'
+
+export function shallow<T>(objA: T, objB: T) {
+  if (Object.is(objA, objB)) {
+    return true
+  }
+
+  if (
+    typeof objA !== 'object' ||
+    objA === null ||
+    typeof objB !== 'object' ||
+    objB === null
+  ) {
+    return false
+  }
+
+  if (objA instanceof Map && objB instanceof Map) {
+    if (objA.size !== objB.size) return false
+    for (const [k, v] of objA) {
+      if (!objB.has(k) || !Object.is(v, objB.get(k))) return false
+    }
+    return true
+  }
+
+  if (objA instanceof Set && objB instanceof Set) {
+    if (objA.size !== objB.size) return false
+    for (const v of objA) {
+      if (!objB.has(v)) return false
+    }
+    return true
+  }
+
+  if (objA instanceof Date && objB instanceof Date) {
+    if (objA.getTime() !== objB.getTime()) return false
+    return true
+  }
+
+  const keysA = getOwnKeys(objA)
+  if (keysA.length !== getOwnKeys(objB).length) {
+    return false
+  }
+
+  // eslint-disable-next-line @typescript-eslint/prefer-for-of
+  for (let i = 0; i < keysA.length; i++) {
+    if (
+      !Object.prototype.hasOwnProperty.call(objB, keysA[i] as string) ||
+      !Object.is(objA[keysA[i] as keyof T], objB[keysA[i] as keyof T])
+    ) {
+      return false
+    }
+  }
+  return true
+}
+
+function getOwnKeys(obj: object): Array<string | symbol> {
+  return (Object.keys(obj) as Array<string | symbol>).concat(
+    Object.getOwnPropertySymbols(obj),
+  )
+}

frontend/node_modules/@tanstack/react-store/src/useStore.ts

@@ -0,0 +1,44 @@
+import { useCallback } from 'react'
+import { useSyncExternalStoreWithSelector } from 'use-sync-external-store/shim/with-selector'
+import type { AnyAtom } from '@tanstack/store'
+
+type SyncExternalStoreSubscribe = Parameters<
+  typeof useSyncExternalStoreWithSelector
+>[0]
+
+function defaultCompare<T>(a: T, b: T) {
+  return a === b
+}
+
+export function useStore<TAtom extends AnyAtom | undefined, T>(
+  atom: TAtom,
+  selector: (
+    snapshot: TAtom extends { get: () => infer TSnapshot }
+      ? TSnapshot
+      : undefined,
+  ) => T,
+  compare: (a: T, b: T) => boolean = defaultCompare,
+): T {
+  const subscribe: SyncExternalStoreSubscribe = useCallback(
+    (handleStoreChange) => {
+      if (!atom) {
+        return () => {}
+      }
+      const { unsubscribe } = atom.subscribe(handleStoreChange)
+      return unsubscribe
+    },
+    [atom],
+  )
+
+  const boundGetSnapshot = useCallback(() => atom?.get(), [atom])
+
+  const selectedSnapshot = useSyncExternalStoreWithSelector(
+    subscribe,
+    boundGetSnapshot,
+    boundGetSnapshot,
+    selector,
+    compare,
+  )
+
+  return selectedSnapshot
+}