feat(examples): Add visualizer

[ciscorn]

Add a simple egui-based visualizer to help understand earcut's behavior.

---

• I agree to follow the project's code of conduct.
• I added an entry to the project's change log file if knowledge of this change could be valuable to users.
  • Usually called CHANGES.md or CHANGELOG.md
  • Prefix changelog entries for breaking changes with "BREAKING: "

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.72%. Comparing base (fffa65f) to head (3d98303).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #44      +/-   ##
==========================================
- Coverage   99.73%   99.72%   -0.01%     
==========================================
  Files           3        3              
  Lines        1859     1851       -8     
==========================================
- Hits         1854     1846       -8     
  Misses          5        5              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Copilot]

Pull request overview

Adds an interactive egui-based example to visualize earcut triangulation behavior, while also adjusting the public triangulation API/docs and repo examples/dependencies.

Changes:

• Add examples/visualizer.rs (interactive viewer with fixture selection, pan/zoom, and optional Delaunay overlay).
• Update Earcut::earcut / EarcutI32::earcut docs and refactor implementation (including removal of earcut_impl and some debug assertions).
• Remove the old profile_loop example and add dev-dependencies + explicit example target in Cargo.toml.

Reviewed changes

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

Show a summary per file

File	Description
src/lib.rs	Adds panic docs, inlines implementation previously routed via earcut_impl, and removes z_order debug assertions.
src/int.rs	Adds panic docs and inlines implementation previously routed via a private helper.
examples/visualizer.rs	New eframe/egui visualizer example using test fixtures and optional Delaunay triangulation overlay.
examples/profile_loop.rs	Removes the profiling-loop example.
Cargo.toml	Adds eframe/spade dev-deps and declares the new visualizer example target.

---

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

[Copilot]

Pull request overview

Copilot reviewed 6 out of 7 changed files in this pull request and generated 6 comments.

---

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

[Copilot]

Pull request overview

Copilot reviewed 6 out of 7 changed files in this pull request and generated 3 comments.

---

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

[Copilot]

Pull request overview

Copilot reviewed 6 out of 7 changed files in this pull request and generated 4 comments.

Comments suppressed due to low confidence (1)

src/lib.rs:244

• This PR removes the previously-public earcut_impl entry point (it was being called here before the refactor). Removing a public method is a breaking API change; if this wasn’t intended, consider keeping earcut_impl as a thin wrapper (optionally #[deprecated]) to preserve backward compatibility, or otherwise document it as a breaking change and add a changelog entry / version bump accordingly.

    pub fn earcut<N: Index>(
        &mut self,
        data: impl IntoIterator<Item = [T; 2]>,
        hole_indices: &[N],
        triangles_out: &mut Vec<N>,

---

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