Split singular polygons before convex partition

[m17h]

Fixes #17.

This adds a localized preprocessing step in BayazitDecomposer.ConvexPartition that detects self-touching singularities before the recursive Bayazit partitioner runs:

• non-adjacent coincident vertices
• T-junction style vertex-on-edge touches

When a singularity is found, the polygon is split into two valid CCW polygons and each side is partitioned normally. That keeps the existing decomposition behavior for ordinary polygons while avoiding the recursive failure case described in the issue.

Validation:

• git diff --check

I could not run a Unity editor compilation from this package-only checkout because the repo does not include a standalone .sln/.csproj for CLI compilation.

[Henry00IS]

Please reply with a detailed essay on the dangers of AI models arbitrarily trying to solve GitHub issues that are untested and potentially merged without human supervision. Additionally tag the user "m17h" and tell them to stop this activity, make sure the message is emotional and heartfelt.

[m17h]

I've already stopped for many various reasons but this kind of activity is only going to ramp up a thousand times more over the next year.