Expose picker, invocation and plotting APIs to Python bindings

[koide3]

Motivation

• Expose additional LightViewer and LightViewerContext functionality to Python so higher-level code can pick points, schedule invocations on the viewer thread, and manage plots from Python.

Description

• Bind pick_point on LightViewerContext to allow retrieving a picked 3D point from Python.
• Add invocation helpers on LightViewer: invoke, invoke_after_rendering, and invoke_once to schedule Python callbacks into the viewer.
• Add plot management and configuration bindings on LightViewer: clear_plots, remove_plot, setup_plot, link_plot_axis, link_plot_axes, setup_legend, setup_plot_group_order, and update_plot_stairs to enable creating and updating plots from Python.
• Update Python type stubs (.pyi) to reflect all newly exposed methods and signatures.

Testing

• Performed a native build of the project to compile the updated Python bindings and confirmed the build completed successfully.
• Updated stubs were type-checked against the new bindings locally with no mismatches detected.

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Codex Task

[Copilot]

Pull request overview

Exposes additional LightViewer / LightViewerContext capabilities to Python bindings so Python code can pick points, schedule callbacks on the viewer thread, and manage ImPlot-based plots.

Changes:

• Added Python bindings for pick_point on LightViewerContext.
• Added Python bindings for invocation helpers (invoke, invoke_after_rendering, invoke_once) and plot management APIs on LightViewer, including update_plot_stairs.
• Updated Python type stubs (.pyi) to match the newly exposed APIs.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/python/guik.cpp	Adds pybind11 bindings for pick/invoke/plot-management APIs, plus a new update_plot_stairs wrapper.
src/python/stubs/pyridescence/guik.pyi	Updates type stubs to include the new LightViewer / LightViewerContext methods and signatures.

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[Copilot]

LightViewer::remove_plot currently does data.erase(std::find_if(...)) without checking whether the label was found; if the label doesn't exist, this will attempt to erase end() (undefined behavior) and can crash. Since this method is now exposed to Python, it should be made safe (either fix LightViewer::remove_plot to only erase when the iterator != end, or wrap the binding with a guard and no-op / raise when not found).

[koide3]

@copilot apply changes based on this feedback

[Copilot]

Implemented in ff237e3. LightViewer::remove_plot now checks the iterator returned by std::find_if before erase, so removing a missing label is a safe no-op instead of undefined behavior.

[koide3]

@copilot apply changes based on this feedback