chore: add GEMINI.md project guidelines with mandatory git protocol

GEMINI.md

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+# DoorNroll Project Guidelines & Rules
+
+## 1. Mandatory Git Protocol (CRITICAL)
+- **Always Commit**: Any modifications, features, refactors, or bugfixes must be committed to Git as soon as they are implemented and verified.
+- **Always Push**: Every commit must be pushed immediately to the remote repository:
+  ```bash
+  git push origin main
+  # Remote: https://git.silverstone.crazedns.ru/iker_ad/DoorNroll.git
+  ```
+- **Working Tree**: Keep the Git working tree clean after every task.
+
+## 2. Visual & Geometric Design Rules (Zero-Rounding)
+- **Zero Rounding**: Absolutely NO circles, rounded corners, or smooth curved UI primitives (`DrawCircle`, `DrawCircleLines`, `DrawSphere`, `DrawRing`, `DrawRectangleRounded`).
+- **Tactical Industrial Aesthetic**: All shapes must be angular, faceted, rectangular, or polygon-based (hard-surface, military electronics, cyber-noir).
+- **Color Palette**: High-contrast monochrome, gunmetal, dark slate graphite, and smoked wood base, with saturated functional accents:
+  - Kinetic: `KIN` Titanium White
+  - EMP: `EMP` Cobalt Blue
+  - Overheat: `THM` Amber
+  - Corrosive: `ACD` Acid Green
+  - Glitch: `GLT` Neon Violet
+  - Nanite: `NAN` Carmine / Crimson
+  - Active Firing Pin / Critical HUD: Pure White & Crimson
+
+## 3. 3D Rendering Architecture
+- **Pipeline Order in Rooms**:
+  1. Opaque geometry rendered first (floor, walls, ceiling, furniture).
+  2. Flush opaque batch (`rlDrawRenderBatchActive()`).
+  3. Translucent pass with `BeginBlendMode(BLEND_ALPHA)`, `rlDisableDepthMask()`, `rlDisableBackfaceCulling()` (godrays, glass, light pools, energy fields).
+  4. Flush translucent batch (`rlDrawRenderBatchActive()`), restore depth mask & blend mode.
+  5. Post-process shader pass (`beginPostProcess` / `endPostProcess`).
+
+## 4. Build & Environment
+- **Platform**: Windows, MSVC C++20, CMake 3.20+, Raylib 5.5.
+- **Verification**: Always run CMake build in Release mode before concluding work:
+  ```powershell
+  & "C:\Program Files (x86)\Microsoft Visual Studio\18\BuildTools\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe" --build build --config Release
+  ```