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/Fonts/SourceHanSansSC-Regular.otf.meta

@@ -0,0 +1,21 @@
+fileFormatVersion: 2
+guid: ce5da230aa9d2439c998f40a36e72588
+TrueTypeFontImporter:
+  externalObjects: {}
+  serializedVersion: 4
+  fontSize: 16
+  forceTextureCase: -2
+  characterSpacing: 0
+  characterPadding: 1
+  includeFontData: 1
+  fontNames:
+  - Source Han Sans SC
+  fallbackFontReferences: []
+  customCharacters: 
+  fontRenderingMode: 0
+  ascentCalculationMode: 1
+  useLegacyBoundsCalculation: 0
+  shouldRoundAdvanceValue: 1
+  userData: 
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