feat: establish the workshop-rs catalog provider seam

[Teakowa]

Summary

• Consumes the released workshop-rs 0.1.1 crate from crates.io and raises the MSRV to Rust 1.85.
• Adds the del-rs-owned CatalogProvider backed only by canonical workshop-rs catalog APIs.
• Resolves ExternalPosition::Type enum domains through Catalog::enum_domain, returning canonical ExternalTypeInfo without querying Kind::Enum entries.
• Preserves direct value/action canonical IDs and catalog parameter metadata, including parameter names and optional/default status; NoopProvider remains available.
• Adds WorkshopSourceBridge, a source-only DEL-owned bridge from SourceMap files and byte spans to a workshop-rs SourceFile arena plus typed FileId/1-based Position/Span.
• Documents del-rs Lower core DEL HIR into canonical workshop-rs WIR #30 as the DEL-owned HIR-to-WIR lowering adapter; canonical WIR/catalog/emission contracts remain owned by workshop-rs. No copied catalog data or backend encoding is added here.

Evidence

• cargo build --locked --all-targets
• cargo test --locked --all-targets
• cargo test --locked --test workshop_provider --test matrix --test corpus
• provider tests: 8 passed, including Team enum type, direct Add value identity/parameters, and SmallMessage optional/default metadata
• source-bridge tests: 3 passed, covering cross-file typed identity, Unicode scalar columns, 1-based line/newline/EOF boundaries, and explicit invalid-location errors
• cargo metadata --locked and cargo tree --locked: registry workshop-rs v0.1.1
• changed-file rustfmt checks and git diff --check
• GitHub Actions test passed for commit 0d9db8b

Closes #29
Parent: #8
Canonical event contract: workshop-rs#12, shipped in workshop-rs 0.1.1.