[PBT] Infer bounded numeric relations from observations

[CaelmBleidd]

Part of #397: evaluate numeric equality (===) and order (<=) candidates from the existing property-observation artifacts. The caller explicitly selects two operands of the same assertion and call site; the result retains the exact observations, source hashes, and build status.

Agreement requires at least two distinct admitted fast-check generation inputs and two distinct observed numeric pairs. Replay, shrinking, and solver observations may refute a candidate but cannot add independent support. Empty, incomplete, unsupported, and refuted evidence remain separate outcomes. Comparisons follow JavaScript binary64 behavior, including NaN, infinities, and signed zero.

This is a bounded first slice: one observation per selected point and invocation, no nested invocation matching, automatic operand discovery, affine relations, or symbolic-search integration. The result is an empirical candidate, not a proven invariant. It may repeat the original predicate or domain because this slice does not inspect their formulas. #397 remains open.

Validation: 16 focused inference tests and one real fast-check capture-to-inference test pass; strict PBT Detekt (main/test) and git diff --check pass. No experiment campaign was run.