Fix review findings: toggle logic, preset saving, version lookup, async audio ops

- Fix inverted effects toggle in FloatingGenerateBox
- Add Save button + API method for editing custom effect presets
- Return early on effects save failure in ProfileForm
- Fix no-op ternary in effectsStore
- Handle duplicate preset names with proper 400 response
- Use effects_chain is None instead of label for clean version lookup
- Move blocking audio ops to asyncio.to_thread in async endpoints
- Log warnings instead of silently swallowing parse errors

app/src/components/Generation/FloatingGenerateBox.tsx

@@ -393,8 +393,9 @@ export function FloatingGenerateBox({
                           variant="ghost"
                           size="icon"
                           onClick={() => {
-                            setIsEffectsMode(!isEffectsMode);
-                            if (isEffectsMode) setIsInstructMode(false);
+                            const next = !isEffectsMode;
+                            setIsEffectsMode(next);
+                            if (next) setIsInstructMode(false);
                           }}
                           className={cn(
                             'h-10 w-10 rounded-full transition-all duration-200',