Remove signal restriction logic from SelectedObject shader pipeline

[Copilot]

Strip hasSignalRestriction, startAngle, and endAngle from the SelectedObject rendering path — these were placeholder fields (hardcoded to 0) with unused angle-based fragment discard logic.

• SelectedObjectVertexData: Reduced to float pos[2] only
• Shaders (VS/GS/FS): Removed signal restriction attributes, pass-through varyings, and angle-range fragment logic; FS now renders a simple white ring
• RenderPipeline.cpp: Removed vertex attribute bindings for locations 1–3
• GeometryKernels.cu: Removed dead field assignments in cudaExtractSelectedObjectData for both cells and energy particles

// Before
struct SelectedObjectVertexData {
    float pos[2];
    int hasSignalRestriction;
    float startAngle;
    float endAngle;
};

// After
struct SelectedObjectVertexData {
    float pos[2];
};

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