Add external compile-contract tests for renamed public Rust APIs #401

Summary

Add external compile-contract tests for public Rust API changes in pull request #363.

Rationale

The pull request renames public APIs and removes rasterise_signal. Existing integration tests and doctests compile selected call sites, but they do not define the complete external API contract or intentional removal of legacy names.

Affected areas

• crates/whitaker_sarif/src/lib.rs
• crates/whitaker_sarif/src/model/
• crates/whitaker_sarif/src/builders/run_builder.rs
• common/src/lib.rs
• common/src/i18n/
• common/src/complexity_signal.rs
• crates/bumpy_road_function/src/analysis.rs

Required changes

• Add a Rust compile-time test harness, such as trybuild, that compiles as an external API consumer.
• Add a pass case that constructs Artefact, ArtefactLocation, PhysicalLocation::artefact_location, and Run::artefacts.
• Add a pass case that calls RunBuilder::with_artefact.
• Cover the renamed public normalize_locale, normalize_settings, and rasterize_signal APIs where each crate exposes them.
• Add compile-fail cases for removed legacy names when the breaking API contract requires explicit rejection.
• Keep dynamic values out of snapshots or diagnostics.

Acceptance criteria

• The harness compiles API-consumer pass cases against public crate exports.
• The harness verifies the renamed APIs named above.
• Compile-fail tests verify required legacy-name rejection.
• The tests remain stable across supported toolchains.

Backlinks

• Pull request: Correct en-GB-oxendict spellings in code symbols and prose #363
• Requesting comment: Correct en-GB-oxendict spellings in code symbols and prose #363 (comment)
• Requested by: @leynos