[TS PBT] Retain residual unknown-call diagnostics in property results

[CaelmBleidd]

Stopped calls such as Array::slice() and Float64Array::constructor already expose their callee, failure reason, and source statement through TsUnknownCallEvent, but public property-search results retained only a generic unsupported-call message. The auxiliary relation-refutation prefix also dropped that event.

The existing bounded runtime-limitation observer now retains actual stop/fresh-return fallback decisions with stable diagnostic codes, the original callee and failure reason, and the shared source-origin/fallback location. Successfully applied models do not become limitations. Runtime and unknown-call diagnostics share the existing 64 distinct-record limit and truncation marker. The auxiliary observer delegates the same event to that collector. No core, selector, execution policy, semantic model, or original experiment source was changed.

Validation: 33 focused tests pass across the public property search, auxiliary entry-refutation, and bounded observer contracts; usvm-ts-pbt:detektMain, usvm-ts-pbt:detektTest, usvm-ts-fast-check:detektTest, and git diff --check pass. Both new public regressions fail on the parent observer because the expected diagnostic is absent, even though the engine logs the precise stopped call. JSON round trips retain the exact call/reason and original source lines for slice, typed-array construction, and the admission prefix. Controls cover applied models, fresh-return decisions, deduplication, fallback locations, and the shared diagnostic bound.

Refs #555. Depends on #603, including its early-stop and canonical-confirmation follow-up.