Lower core DEL HIR into canonical workshop-rs WIR

[Teakowa]

Parent: #8

Goal

Implement the first production lowering path from validated typed DEL HIR into workshop_rs::wir::Program for the core DEL/OSTW surface, using canonical Workshop identities and returning structured diagnostics for constructs whose runtime lowering is not yet implemented.

Context

The Workshop integration boundary is concrete: released workshop-rs 0.1.1 provides the canonical catalog/WIR contract, including the full reviewed rule-event surface from workshop-rs#12, and #29 establishes the direct dependency/catalog provider seam.

This issue should prove the HIR -> canonical WIR boundary before adding the more complex object/reference runtime encodings tracked separately.

Scope

• Build canonical WIR file/source provenance from the DEL source registry.
• Allocate global variables, player variables, and subroutines deterministically, honoring evidence-backed explicit source IDs/reservations where applicable.
• Lower top-level initializers into correct Workshop initialization behavior without adding semantics to workshop-rs.
• Lower core rules, conditions, actions, values, literals, arrays, canonical enum constants, external Workshop calls, assignments/modifications, and subroutine calls.
• Lower supported control flow, including if, while, and direct Workshop for forms where the current HIR carries sufficient intent.
• Lower the declared DEL rule-event inventory through the canonical event contract shipped in workshop-rs 0.1.1; do not introduce a local event representation.
• Resolve Workshop calls/constants using canonical bindings produced by the catalog-backed provider from Establish the workshop-rs dependency and canonical catalog provider #29.
• Validate every produced program through workshop_rs::wir::Program::validate and canonical Workshop validation where applicable.
• Preserve DEL spans/provenance on WIR variables, rules, actions, and values wherever the public WIR model supports it.
• Add focused positive/negative tests tying each supported lowering category to DEL corpus evidence and canonical WIR invariants.
• Return stable structured lowering diagnostics for advanced/runtime/project constructs not yet supported; never silently drop or approximate them as successful compilation.

Non-goals

• Class/object allocation, delete, stale-reference generation checks, virtual dispatch, recursion stacks, closure runtime encoding, or other advanced runtime layout decisions.
• Duplicating catalog/WIR/emitter logic from workshop-rs.
• Matching upstream helper names, variable layouts, formatting, optimizer output, or temporary variables unless observable semantics require them.
• Full CLI/end-to-end compiler compatibility claim.

Acceptance criteria

• Representative core DEL/OSTW programs lower from validated HIR to structurally valid canonical WIR.
• Workshop actions/values/enums/events in produced WIR use canonical catalog identities, not localized or provider-specific spellings.
• Global/player variable and subroutine identities are deterministic and evidence-backed.
• Source provenance survives into WIR diagnostics for representative cross-file cases.
• Unsupported advanced constructs fail explicitly with structured diagnostics rather than producing semantically incomplete WIR.
• Existing Workshop-independent parse/check/inspect/HIR tests remain regression-green.

Dependencies

• Establish the workshop-rs dependency and canonical catalog provider #29 — released workshop-rs 0.1.1 dependency, provider, and provenance bridge.
• wrightkit/workshop-rs#12 — complete; its event contract is already included in workshop-rs 0.1.1.