Epic: Support Swift examples across the benchmark registry

[DavidBakerEffendi]

Goal

Add Swift as a first-class example language across DataFlowBench's applicable registry families, with reproducible reference-analyzer execution and honest coverage reporting. Swift is present in the audited CodeQL and Joern language inventories but absent from Bifrost's 13 targets and the benchmark's Swift fixtures.

This is benchmark work, not a request to implement Swift in Bifrost. Bifrost support is not a prerequisite; its Swift coverage must remain explicitly unsupported until implemented and verified.

Scope and completion contract

• Audit every current registry family: calibration, propagation/core, challenge, recursive composition, modeling, tool-native profiles, and real-project populations. Record a Swift implementation or an explicit applicability/deferred-scope decision for each; do not silently omit families.
• Implement balanced, analyzer-neutral Swift examples for applicable executable synthetic families, retaining stable template identities and idiomatic semantics.
• Keep value-flow, typestate, and performance tracks reserved where they have no executable cases; this epic does not silently activate new tracks or commission a new real-project study.
• Integrate CodeQL and Joern independently after pinned-binary activation probes. A listed frontend alone is not proof of usable taint analysis.
• Preregister scored partitions before scored execution; preserve typed unsupported/inconclusive/runner-error outcomes, exact provenance, and immutable historical freezes.
• Publish Swift coverage and results only from validated new evidence, clearly separating analyzer breadth, fixture participation, and measured support.

Subissues below define ownership and sequencing. Final completion requires all applicable executable families to be covered; any remaining deferral must be explicit and accepted rather than hidden in a completion claim.

Subissues

• Define Swift applicability across all registry families #216 — Define Swift applicability across all registry families
• Implement Swift fixtures and registry validation #217 — Implement Swift fixtures and registry validation
• Integrate CodeQL execution for Swift registry examples #218 — Integrate CodeQL execution for Swift registry examples
• Integrate Joern execution for Swift registry examples #219 — Integrate Joern execution for Swift registry examples
• Validate and publish Swift registry coverage and reference results #220 — Validate and publish Swift registry coverage and reference results