Release 1.1.2 — the default path works end to end

Fix release for 1.1.1: the minimal path end to end, engine commands that
run on Godot, Unity and Unreal, hook warnings you can see, and verdicts
that say when they could not check. Details in CHANGELOG.md; upgrade
steps in UPGRADING.md (v1.1.1 → v1.1.2).

Fixes #67
Fixes #131

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WuJn2FdynEybfL5KC697nJ

.claude/rules/shader-code.md

@@ -1,11 +1,15 @@
 ---
 paths:
   - "assets/shaders/**"
+  - "**/*.gdshader"
+  - "Assets/**/*.{shader,hlsl,cginc,compute,shadergraph}"
+  - "Shaders/**"
+  - "**/*.{usf,ush}"
 ---
 
 # Shader Code Standards
 
-All shader files in `assets/shaders/` must follow these standards to maintain
+All shader files, in every engine, must follow these standards to maintain
 visual quality, performance, and cross-platform compatibility.
 
 ## Naming Conventions
@@ -14,7 +18,8 @@ visual quality, performance, and cross-platform compatibility.
   - `SG_Env_Water` (Unity Shader Graph)
   - `M_Env_Water` (Unreal Material)
 - Use descriptive names that indicate the material purpose
-- Prefix with shader type: `spatial_`, `canvas_`, `particles_`, `post_`
+- Prefix with the engine's shader type — Godot `spatial_`, `canvas_`, `particles_`,
+  `post_`; Unity `SG_` (Shader Graph); Unreal `M_`, `MI_` (instance), `MF_` (function)
 
 ## Code Quality
 - All uniforms/parameters must have descriptive names and appropriate hints
@@ -27,7 +32,8 @@ visual quality, performance, and cross-platform compatibility.
 - Document the target platform and complexity budget for each shader
 - Use appropriate precision: `half`/`mediump` on mobile where full precision isn't needed
 - Minimize texture samples in fragment shaders
-- Avoid dynamic branching in fragment shaders — use `step()`, `mix()`, `smoothstep()`
+- Avoid dynamic branching in fragment shaders — use `step()`, `smoothstep()` and
+  `mix()` (Godot, GLSL) or `lerp()` (HLSL: Unity, Unreal)
 - No texture reads inside loops
 - Two-pass approach for blur effects (horizontal then vertical)