mesh: exact predicates (Shewchuk adaptive, symbolic perturbation, indirect LPI/TPI) (#8)

* mesh: exact predicates (Shewchuk adaptive orient/incircle/insphere), symbolic perturbation, indirect LPI/TPI predicates

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* mesh: predicate benchmark (filter hit rate, CAD-degenerate inputs); record the predicate decision

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* mesh: simplify predicates (destructuring over fallbacks, shared-minor exact insphere, cheaper expansion product)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

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Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

crates/mesh/src/lib.rs

@@ -20,3 +20,5 @@ pub enum Error {
 }
 
 pub type Result<T> = std::result::Result<T, Error>;
+
+pub mod predicates;