Add getters to Renderer and Preprocessor

[LioQing]

• Added bind_group_layout, pre_bundle, bundle, post_bundle, and bind_group getters in Preprocessor
• Added bind_group_layout, pipeline, and bind_group getters in Renderer
• Remove warning for active development, we're starting to slow down new feature additions

Close #7

[Copilot]

Pull request overview

This PR expands the public API surface of the viewer’s rendering components by exposing internal WGPU resources via accessor methods, making it easier for downstream users to integrate/customize pipelines without re-plumbing internals.

Changes:

• Added getters on Renderer for bind_group_layout, pipeline, and bind_group.
• Added getters on Preprocessor for bind_group_layout, pre_bundle, bundle, post_bundle, and bind_group.
• Updated project docs/artifacts (changelog entry, README warning removal, regenerated coverage report).

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/renderer.rs	Adds public accessors for renderer bind group layout, pipeline, and bind group.
src/preprocessor.rs	Adds public accessors for bind group layout, compute bundles, and bind group.
coverage/lcov.info	Regenerated coverage output reflecting newly added getter functions.
README.md	Removes the “breaking changes” warning block from the overview section.
CHANGELOG.md	Adds a “Next release” entry documenting the new getters.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.