Fix integer truncation in CatchBeatmapProcessor time delta calculation

Changed `timeDiff` calculation from `int` to `double` in `applyHardRockOffset` to prevent precision loss which was affecting randomization and offset application.
Updated expected values for `CatchBeatmapConversionTest` case `1431386` as the fix alters Hard Rock object positions.
Added `CatchBeatmapProcessorTest` to verify the fix.
Fixed code style issues (license header, object initializer, formatting).

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>

Author: google-labs-jules[bot]

osu.Game.Rulesets.Catch.Tests/CatchBeatmapProcessorTest.cs

@@ -1,11 +1,11 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System.Collections.Generic;
 using NUnit.Framework;
 using osu.Game.Beatmaps;
 using osu.Game.Rulesets.Catch.Beatmaps;
 using osu.Game.Rulesets.Catch.Objects;
-using System.Collections.Generic;
 
 namespace osu.Game.Rulesets.Catch.Tests
 {