Decompose 304-line inferType into per-template-kind helpers (#207)

inferType was a chain of template-kind blocks, each ending in return.
Each kind is now a tryInfer* helper returning true when handled:
tryInferNamedGeneric, tryInferClass, tryInferInterface, tryInferArray,
tryInferTuple (shared field walk via template helper), tryInferOptional,
tryInferFunction, tryInferUnion. The conditional-type and typeref tail
stays in the driver because the conditional block intentionally leaves
its false branch for the typeref check. Bodies moved verbatim; driver
is now a readable dispatch list.

Review doc item (section 5).

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: ASDAlexander77