add-series-type

name	add-series-type
description	Adds a new Spectra plot series type end-to-end — core model, shaders, Vulkan pipeline, renderer draw path, and tests. Use for bar charts, heatmaps, contours, or new 2D/3D series in src/core/ and src/render/.

Add Series Type

1. Public header in include/spectra/ if API-facing
2. Implementation in src/core/ (Series / Series3D)
3. Rendering:
   • Shaders: add-shader
   • Pipeline: src/render/vulkan/vk_pipeline.cpp
   • Draw: src/render/renderer.cpp
4. Wire Axes / Axes3D factory (e.g. ax.bar(...))
5. Dirty flag for incremental GPU upload
6. tests/unit/ + golden if visual
7. examples/ demo

Conventions

• Input: std::span<const float>
• Builder-style config (.color(), .label(), …)
• Match existing LineSeries / ScatterSeries patterns

3D series: 3d-rendering.