Complete Scala human ground-truth audit

[DavidBakerEffendi]

Description

Completes the human-reviewed Scala ground-truth audit for issue #58 and calibrates the authored contracts against Metals 1.6.7 and Bifrost 0.8.9.

Key Changes:

• Reviews and documents 15 planned Scala cases across baseline, precision, and LSP-parity fixtures.
• Reclassifies Scala def declarations from function to method where appropriate and distinguishes singleton objects from true companion objects.
• Makes declaration-versus-definition navigation explicit for fields, stable vals, constructors, methods, aliases, and extension methods.
• Splits trait-family references from exact concrete override dispatch so statically concrete calls are not accepted as interface-family noise.
• Replaces the empty synthetic placeholder with compiling, planned case-class coverage for generated apply, copy, named component arguments, and accessors.
• Records Metals query-order sensitivity and Bifrost gaps around trait-family expansion and synthesized-member receiver recovery.
• Updates the analyzer comparison documentation with the reviewed Scala distinctions.

Touch Points:

• benchmarks/cases/scala-{baseline,precision,lsp-parity}.yaml
• benchmarks/reviews/2026-07-17-DavidBakerEffendi.md
• fixtures/scala/lsp-parity/src/main/scala/example/Workflow.scala
• docs/src/content/docs/results/case-comparison.md

Validation:

• All three Scala fixture roots compile with sbt 1.11.7 and Scala 3.7.3 through the pinned Metals profile.
• cargo fmt --check
• RUSTDOC=/Users/dave/.rustup/toolchains/stable-aarch64-apple-darwin/bin/rustdoc cargo test (105 passed)
• cargo run -- validate benchmarks/cases (35 documents)
• Full Metals aggregate: 6 pass, 6 semantic failures, 3 Declaration-unsupported.
• Full Bifrost Scala aggregate: 12 pass, 3 semantic failures.

Advances #58; TypeScript remains for the final language audit.