feat: add Unity 6 client with 2.5D visual system

Unity client features:
- WebSocket connection via NativeWebSocket
- 2.5D agent visuals with programmatic placeholder sprites
- Billboard system for sprites and UI elements
- Floating UI panels (name, HP, energy bars)
- Speech bubble system with pop-in animation
- RTS-style camera controller (WASD + scroll zoom)
- Editor tools for prefab creation and scene setup

Scripts:
- NetworkManager: WebSocket singleton
- GameManager: Agent spawning and event handling
- AgentVisual: 2.5D sprite and UI creation
- Billboard: Camera-facing behavior
- SpeechBubble: Animated dialogue display
- CameraController: RTS camera with UI input detection
- UIManager: HUD and command input

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

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

unity-client/Assets/TextMesh Pro/Shaders/TMPro.cginc

@@ -0,0 +1,84 @@
+float2 UnpackUV(float uv)
+{ 
+	float2 output;
+	output.x = floor(uv / 4096);
+	output.y = uv - 4096 * output.x;
+
+	return output * 0.001953125;
+}
+
+fixed4 GetColor(half d, fixed4 faceColor, fixed4 outlineColor, half outline, half softness)
+{
+	half faceAlpha = 1-saturate((d - outline * 0.5 + softness * 0.5) / (1.0 + softness));
+	half outlineAlpha = saturate((d + outline * 0.5)) * sqrt(min(1.0, outline));
+
+	faceColor.rgb *= faceColor.a;
+	outlineColor.rgb *= outlineColor.a;
+
+	faceColor = lerp(faceColor, outlineColor, outlineAlpha);
+
+	faceColor *= faceAlpha;
+
+	return faceColor;
+}
+
+float3 GetSurfaceNormal(float4 h, float bias)
+{
+	bool raisedBevel = step(1, fmod(_ShaderFlags, 2));
+
+	h += bias+_BevelOffset;
+
+	float bevelWidth = max(.01, _OutlineWidth+_BevelWidth);
+
+  // Track outline
+	h -= .5;
+	h /= bevelWidth;
+	h = saturate(h+.5);
+
+	if(raisedBevel) h = 1 - abs(h*2.0 - 1.0);
+	h = lerp(h, sin(h*3.141592/2.0), _BevelRoundness);
+	h = min(h, 1.0-_BevelClamp);
+	h *= _Bevel * bevelWidth * _GradientScale * -2.0;
+
+	float3 va = normalize(float3(1.0, 0.0, h.y - h.x));
+	float3 vb = normalize(float3(0.0, -1.0, h.w - h.z));
+
+	return cross(va, vb);
+}
+
+float3 GetSurfaceNormal(float2 uv, float bias, float3 delta)
+{
+	// Read "height field"
+  float4 h = {tex2D(_MainTex, uv - delta.xz).a,
+				tex2D(_MainTex, uv + delta.xz).a,
+				tex2D(_MainTex, uv - delta.zy).a,
+				tex2D(_MainTex, uv + delta.zy).a};
+
+	return GetSurfaceNormal(h, bias);
+}
+
+float3 GetSpecular(float3 n, float3 l)
+{
+	float spec = pow(max(0.0, dot(n, l)), _Reflectivity);
+	return _SpecularColor.rgb * spec * _SpecularPower;
+}
+
+float4 GetGlowColor(float d, float scale)
+{
+	float glow = d - (_GlowOffset*_ScaleRatioB) * 0.5 * scale;
+	float t = lerp(_GlowInner, (_GlowOuter * _ScaleRatioB), step(0.0, glow)) * 0.5 * scale;
+	glow = saturate(abs(glow/(1.0 + t)));
+	glow = 1.0-pow(glow, _GlowPower);
+	glow *= sqrt(min(1.0, t)); // Fade off glow thinner than 1 screen pixel
+	return float4(_GlowColor.rgb, saturate(_GlowColor.a * glow * 2));
+}
+
+float4 BlendARGB(float4 overlying, float4 underlying)
+{
+	overlying.rgb *= overlying.a;
+	underlying.rgb *= underlying.a;
+	float3 blended = overlying.rgb + ((1-overlying.a)*underlying.rgb);
+	float alpha = underlying.a + (1-underlying.a)*overlying.a;
+	return float4(blended, alpha);
+}
+