feat: various improvements

- Update to MidnightLib 1.7.0 and use its features to make the config screen more reliable
- Fix background gradient being opaque briefly when fading out while not in a world
- Fix 1.21.5 compat (still compatible with 1.21.4 as well :D)

common/src/main/java/eu/midnightdust/blur/mixin/MixinMidnightConfig$EntryInfo.java

@@ -0,0 +1,26 @@
+package eu.midnightdust.blur.mixin;
+
+import eu.midnightdust.blur.Blur;
+import eu.midnightdust.lib.config.MidnightConfig;
+import net.minecraft.client.MinecraftClient;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.util.Objects;
+
+@Mixin(value = MidnightConfig.EntryInfo.class, remap = false)
+public abstract class MixinMidnightConfig$EntryInfo {
+    @Shadow @Final public String modid;
+    @Shadow @Final public String fieldName;
+    @Shadow Object value;
+
+    @Inject(at = @At(value = "TAIL"), method = "updateFieldValue")
+    private void blur$instantlyApplyRadius(CallbackInfo ci) {
+        if (Objects.equals(modid, Blur.MOD_ID) && Objects.equals(fieldName, "radius"))
+            MinecraftClient.getInstance().options.getMenuBackgroundBlurriness().setValue((int) value);
+    }
+}