Add localization support and language settings UI

[StartNight]

Summary

This PR introduces the official Unity Localization package (com.unity.localization v1.5.12) along with Addressables (com.unity.addressables v2.11.1), providing core localization infrastructure, font fallback support, and a dedicated Language tab in the in-game Settings menu.

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Key Changes

1. Package & Asset Configuration

• Added com.unity.localization and com.unity.addressables to Packages/manifest.json.
• Configured Addressable asset groups and schemas for localization data.
• Added Localization Settings with English (en) and Simplified Chinese (zh-Hans) locales and String Tables.
• Added Source Han Sans (SourceHanSansCN-Normal) font asset and configured TextMeshPro fallback font on LiberationSans SDF Custom Outline for seamless multi-language character rendering.

2. Core Architecture & UI

• LocalizationManager: Added localization manager and registered it within SystemGameManager life cycle.
• SystemLanguagePanel: Added a new window panel component that dynamically manages language buttons and syncs highlight states with the active Locale.
• MainSettingsMenuPanel: Added a new "Language" tab navigation and sub-panel activation logic.
• Prefabs: Updated MainMenuPanel and MainSettingsMenuPanel prefabs with the new Language button and sub-panel bindings.

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How to Test

1. Open the project in Unity and enter Play Mode from the Main Menu.
2. Open Settings (or System Menu) -> click on the new Language tab.
3. Switch between English and Chinese (Simplified):
   • Confirm the selected language button is properly highlighted.
   • Confirm localized UI texts and character rendering update accordingly.

[michaelday008]

This looks great! Unfortunately, my Unity is crashing trying to import some of the localization assets. I'll see if I can figure out what's wrong, but if you've seen this before and have any ideas, please let me know.

Start importing Assets/AnyRPG/Core/Content/Localization/Localization Settings.asset using Guid(80e9cb1cac9911646bf50cf5cae97f71) (NativeFormatImporter)
=================================================================
	Native Crash Reporting
=================================================================
Got a UNKNOWN while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

=================================================================
	Managed Stacktrace:
=================================================================
=================================================================
Crash!!!
SymInit: Symbol-SearchPath: 'C:/Program Files/Unity/Hub/Editor/6000.3.10f1/Editor/Data/Mono;.;D:\unity\projects\AnyRPGCoreLocalization;D:\unity\projects\AnyRPGCoreLocalization\Library\BurstCache\JIT;C:\Program Files\Unity\Hub\Editor\6000.3.10f1\Editor;C:\WINDOWS;C:\WINDOWS\system32;', symOptions: 534, UserName: 'anyrpg'
OS-Version: 10.0.0
C:\Program Files\Unity\Hub\Editor\6000.3.10f1\Editor\Unity.exe:Unity.exe (00007FF7DE660000), size: 290816 (result: 0), SymType: '-deferred-', PDB: '', fileVersion: 6000.3.10.24332
C:\WINDOWS\SYSTEM32\ntdll.dll:ntdll.dll (00007FFE42160000), size: 2514944 (result: 0), SymType: '-deferred-', PDB: '', fileVersion: 10.0.26100.8972

[michaelday008]

@StartNight
When I removed the referenced file (Assets/AnyRPG/Core/Content/Localization/Localization Settings.asset) and re-imported, there was no crash, but then I got this following warning, which is I think the root cause. As soon as I moved the file back, the open editor immediately crashed.

AnyRPG Shared Data is already a member of group Localization-String-Tables-English (UnityEditor.AddressableAssets.Settings.AddressableAssetGroup) but group Localization-Assets-Shared contained a reference to it.  Removing reference.
UnityEditor.AssetPostprocessingInternal:PostprocessAllAssets (string[],string[],string[],string[],string[],bool)

Here is what google suggested as the fix. I'm not sure if this makes sense to you

Step 1: Force Unity to Boot Without Triggering the Post-ProcessorClose Unity.Temporarily move Localization Settings.asset out of the project folder again so you can open the editor.Open the project in Unity 6000.3.10f1.Step 2: Clear the Conflicting Reference in the Addressables WindowSince you are in the editor, you can now safely manipulate the groups before they are parsed by the localization system.Open Window > Asset Management > Addressables > Groups.Locate the two groups mentioned in the warning:Localization-String-Tables-EnglishLocalization-Assets-SharedLook for the asset named AnyRPG Shared Data inside both of those groups.The warning indicates Unity tries to auto-remove it from Localization-Assets-Shared. To resolve this permanently, manually select AnyRPG Shared Data from the group it shouldn't belong to, right-click it, and choose Remove Addressable(s) (or drag it so it only natively exists in the correct group).Step 3: Run the Official Localization Addressables AnalyzersUnity provides built-in tools explicitly designed to fix data-corruption mismatches like this before you push to a public repository:In the Addressables Groups window, click on Tools > Analyzers (or Check for Modifications).Look for the Localization Analyzers block.Run the following rules:Check Localization String TablesCheck Localization Asset TablesThe analyzer will flag any duplicate structures or references that would break the dependency tree on a clean import. Click Fix Selected Rules.Go to File > Save Project to save these structural changes into your actual Assets/AddressableAssetsData/ configuration tracking files.Step 4: Verify and CommitClose Unity.Move your Localization Settings.asset file back to its proper home (Assets/AnyRPG/Core/Content/Localization/).Re-open Unity. Because you fixed the double-allocation layout inside the Addressables configuration, the editor will read the setup cleanly, won't trigger the on-the-fly removal warning, and will boot up successfully.Commit your modified AddressableAssetsData files to your Git repository.