[BUG] Lock window size in renders

[BorniaPedro]

Description

Locks the render window size in draw and animate through a two-layer strategy using a VTK ConfigureEvent observer during interactive phases and explicit SetSize re-assertions during non-interactive rendering passes.

Motivation

Dragging, maximizing, or tile-snapping the render window after creation caused screenshots to capture at the resized live window dimensions while text sizes and line widths remained scaled to the initial requested window_size. Additionally, window resizes during the rendering loop of animate resulted in frames of varying dimensions, causing webp.save_images to fail deep in its CFFI layer with an AttributeError: cdata 'struct WebPAnimEncoder *' points to an opaque type. Enforcing the requested window size in both interactive and rendering phases guarantees that saved outputs consistently match the requested dimensions and styling scale.

Relevant Issues

Fixes #265

Changes

• Added a ConfigureEvent observer to the interactor in draw and animate to snap the render window back to the requested dimensions via SetSize upon OS-level resizes.
• Re-asserted SetSize on the render window prior to taking the screenshot in draw and before rendering each frame in animate.

Dependency Updates

None.

Change Magnitude

Minor: Small change such as a bug fix, small enhancement, or documentation update.

Checklist (check each item when completed or not applicable)

• I am familiar with the current contribution guidelines.
• PR description links all relevant issues and follows this template.
• My branch is based on main and is up to date with the upstream main branch.
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• If any major functionality was added or significantly changed, I have added or updated tests in the tests package.
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[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.52%. Comparing base (3f82796) to head (eac5a4b).

Files with missing lines	Patch %	Lines
pterasoftware/output.py	60.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #273      +/-   ##
==========================================
- Coverage   94.56%   94.52%   -0.04%     
==========================================
  Files          47       47              
  Lines        9144     9154      +10     
==========================================
+ Hits         8647     8653       +6     
- Misses        497      501       +4     

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[camUrban]

Hi @BorniaPedro. I'm a bit busy with work at the moment, so I won't be able to review this until next week. Thank you for putting in the time to contribute, it means a lot!