feat: add event log panel, Chinese font support, and documentation

- Add EventLog.cs: scrollable event log panel showing game events
  - Color-coded entries for different event types
  - Toggle visibility, clear button, timestamps
  - Auto-scroll to newest entries

- Add Chinese font support (Source Han Sans SC)
  - SourceHanSansSC-Regular.otf font file
  - ChineseFontSetup.cs editor tool for TMP font asset generation
  - Configure as fallback font for TextMeshPro

- Fix particle system velocity curve warnings in WeatherEffects.cs
  - Ensure all velocity axes use consistent curve mode

- Add comprehensive README.md with project documentation
  - Architecture overview, features, tech stack
  - Quick start guide, Unity client structure
  - Communication protocol, development notes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

unity-client/Assets/Scripts/Visual/WeatherEffects.cs

@@ -191,8 +191,10 @@ namespace TheIsland.Visual
 
             var velocityOverLifetime = _fogSystem.velocityOverLifetime;
             velocityOverLifetime.enabled = true;
-            velocityOverLifetime.x = new ParticleSystem.MinMaxCurve(-0.2f, 0.2f);
-            velocityOverLifetime.y = new ParticleSystem.MinMaxCurve(0.05f, 0.1f);
+            // 所有轴使用相同的曲线模式 (Constant)
+            velocityOverLifetime.x = 0f;
+            velocityOverLifetime.y = 0.08f;
+            velocityOverLifetime.z = 0f;
 
             var colorOverLifetime = _fogSystem.colorOverLifetime;
             colorOverLifetime.enabled = true;
@@ -234,8 +236,10 @@ namespace TheIsland.Visual
 
             var velocityOverLifetime = _heatSystem.velocityOverLifetime;
             velocityOverLifetime.enabled = true;
+            // 所有轴使用相同的曲线模式 (Constant)
+            velocityOverLifetime.x = 0f;
             velocityOverLifetime.y = 1f;
-            velocityOverLifetime.x = new ParticleSystem.MinMaxCurve(-0.3f, 0.3f);
+            velocityOverLifetime.z = 0f;
 
             var colorOverLifetime = _heatSystem.colorOverLifetime;
             colorOverLifetime.enabled = true;
@@ -277,7 +281,10 @@ namespace TheIsland.Visual
 
             var velocityOverLifetime = _cloudSystem.velocityOverLifetime;
             velocityOverLifetime.enabled = true;
+            // 所有轴使用相同的曲线模式 (Constant)
             velocityOverLifetime.x = 0.3f;
+            velocityOverLifetime.y = 0f;
+            velocityOverLifetime.z = 0f;
 
             var renderer = cloudObj.GetComponent<ParticleSystemRenderer>();
             renderer.material = CreateCloudMaterial();