Update project dependencies and configurations; remove deprecated package settings and enhance legacy build support

- Upgrade package manager to pnpm@11.5.2 and remove patched dependencies from package.json.
- Update pnpm-lock.yaml to reflect new dependency versions and remove obsolete entries.
- Refactor Vite configuration to improve legacy build handling, including new plugins for legacy CSS management.
- Remove unused client/index.html file and adjust paths in Vite config for better project structure.
- Enhance DesktopAIShell and EQPage components to support legacy build conditions and improve loading states for raw curves.

client/src/pages/EQPage.tsx

@@ -157,6 +157,7 @@ export default function EQPage() {
   const [selectedCatalogTarget, setSelectedCatalogTarget] = useState<string>("");
   const [isConfirmingTarget, setIsConfirmingTarget] = useState(false);
   const [currentRawCurve, setCurrentRawCurve] = useState<number[] | null>(null);
+  const [rawCurveLoading, setRawCurveLoading] = useState(false);
   const allowPeqRemoteSyncRef = useRef(false);
   const lastPeqCatalogSyncKeyRef = useRef("");
   const syncingHeadphoneRef = useRef(false);
@@ -663,9 +664,13 @@ export default function EQPage() {
       return;
     }
 
+    const copyBrand = currentPeq?.brand?.trim() ?? "";
+    const copyModel = currentPeq?.model?.trim() ?? "";
     const copyPayload: PeqChangePayload = {
       peqChange: {
         name: nextName,
+        ...(copyBrand ? { brand: copyBrand } : {}),
+        ...(copyModel ? { model: copyModel } : {}),
         filters: bands.map(bandToPeqFilter),
         autoPre: currentPeq?.autoPre ?? 0,
         preamp: currentPeq?.preamp ?? 0,
@@ -704,6 +709,8 @@ export default function EQPage() {
           ...prev,
           {
             name: nextName,
+            ...(addPresetMode === "copy" && copyBrand ? { brand: copyBrand } : {}),
+            ...(addPresetMode === "copy" && copyModel ? { model: copyModel } : {}),
             filters: localFilters,
             autoPre: localAutoPre,
             preamp: localPreamp,
@@ -817,15 +824,8 @@ export default function EQPage() {
 
   const loadRawCurveForPeq = useCallback(
     async (peq: { brand?: string; model?: string; name?: string } | undefined): Promise<number[] | null> => {
-      let brand = peq?.brand?.trim() ?? "";
-      let model = peq?.model?.trim() ?? "";
-
-      // Some presets only have `name` (e.g. "Apple AirPods Pro") and miss explicit brand/model.
-      if ((!brand || !model) && peq?.name) {
-        const [first, ...rest] = peq.name.trim().split(/\s+/);
-        if (!brand && first) brand = first;
-        if (!model && rest.length > 0) model = rest.join(" ");
-      }
+      const brand = peq?.brand?.trim() ?? "";
+      const model = peq?.model?.trim() ?? "";
       if (!brand || !model) return null;
 
       const modelCurve = await getModelCurve(brand, model);
@@ -966,11 +966,20 @@ export default function EQPage() {
     syncingHeadphoneRef.current = true;
     setBandsForBothModes(nextBands);
     setSelectedBandByMode({ A: 0, B: 0 });
+    const shouldFetchModelCurve = !!(peq.brand?.trim() && peq.model?.trim());
+    if (shouldFetchModelCurve) {
+      setRawCurveLoading(true);
+      setCurrentRawCurve(null);
+    } else {
+      setRawCurveLoading(false);
+    }
+
     let cancelled = false;
     void (async () => {
       const raw = await loadRawCurveForPeq(peq as { brand?: string; model?: string });
       if (cancelled) return;
       setCurrentRawCurve(raw);
+      setRawCurveLoading(false);
       renderCharts(nextBands, raw, false);
     })();
     requestAnimationFrame(() => {
@@ -1463,6 +1472,7 @@ export default function EQPage() {
         <FreqChart
           bands={bands}
           rawCurve={currentRawCurve}
+          rawCurveLoading={rawCurveLoading}
           selectedBand={selectedBand}
           abMode={abMode}
           onAbToggle={handleAbToggle}