feat(driver): add explicit source provider boundary

[e54-bot]

Summary

• add a Wright-owned source-provider boundary carrying the selected language, entry path, and invocation cwd
• route provider-returned canonical Workshop through workshop-rs and preserve explicit provider-artifact provenance
• surface missing, unsupported, and failed providers as structured diagnostics without native OPY fallback
• add boundary tests and document the ownership boundary

Validation

• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo test --workspace --all-targets --all-features
• cargo test -p wright-driver --test source_provider -- --nocapture
• git diff --check

Scope

This implements the Wright-owned boundary for #243. The concrete LPP adapter is intentionally not included: current LPP v1 cannot carry an entry target, and protocol entry/project loading remains tracked by language-provider-protocol#16. Follow-up provider resolution and workflow wiring remain in #244, #245, and #246.

Refs #243

[Teakowa]

Major — crates/wright-driver/src/source_provider.rs (SourceCompilation)

The product seam cannot carry the source provenance required by #243. It returns diagnostics + canonical Workshop text + locale only, while Loaded::provenance collapses every provider result to ProviderArtifact and all Wright findings become <provider-artifact>. #243 explicitly owns the canonical Workshop + truthful source-provenance contract that #246 is supposed to consume, so #246 would have to redesign this public seam instead of only wiring lint/analyze. Add the approved provenance/unmapped contract to the boundary before merging.

Major — crates/wright-driver/src/session.rs (load_from_source_provider)

Provider-backed OPY stdin is silently converted into a filesystem entry named <stdin>. input::resolve reads the actual stdin text, but SourceTarget discards it and the provider receives ${cwd}/<stdin>, so this path can never represent the user's source. The approved #243 seam is entry-based; reject provider-backed stdin explicitly with a structured diagnostic rather than fabricating an entry path.

Major — crates/wright-driver/src/session.rs (load_from_source_provider Workshop handoff)

Errors while parsing provider-returned canonical Workshop are passed to workshop_diag(error, resolved). workshop_diag stamps Workshop spans with resolved.display, which is the original OPY entry, so a malformed/generated Workshop artifact is falsely reported at OPY source coordinates. Attribute canonical-artifact parse/validation failures to the provider artifact/unmapped provenance instead of the authored OPY path.

[Teakowa]

Major — crates/wright-driver/src/source_provider.rs (SourceProvenance / SourceCompilation)

The previous provenance finding is only partially fixed. Mapped is a flag, but the seam still carries no mapping from canonical Workshop file/span identities to authored OPY source identities/ranges. Consequently resolve_finding_span_paths treats a Mapped provider artifact as if its Workshop file ids already referred to the original source tree, which the boundary cannot establish. #243 requires sufficient truthful provenance for Wright-owned findings where mapping is supported. Carry the actual mapping contract (or keep the result explicitly unmapped); do not expose a Mapped state that cannot be consumed truthfully.

[Teakowa]

LGTM