Retire or commit to legacy public compatibility facades before 1.0

[Teakowa]

Parent: #252

Goal

Ensure every legacy or migration-oriented public compatibility facade is either deliberately supported as part of the 1.x Rust contract or removed before workshop-rs 1.0.

Context

The canonical consumer boundary is the public Workshop Program model plus domain-oriented parsing, validation, analysis, catalog, settings, gameplay, and emission APIs.

Historical compatibility modules and #[doc(hidden)] exports are still semver-relevant when they remain public. Keeping implementation-shaped APIs accidentally would make internal WIR, storage, parser, or layout details part of the 1.x maintenance contract.

Because this work happens before 1.0, removing compatibility-only public APIs is an intentional breaking change. Downstream WrightKit repositories migrate when they adopt the breaking workshop-rs release; their migration is not a prerequisite for owner-side removal.

Scope

• Re-check the current public facade/export inventory against main.
• Remove legacy or hidden public paths that expose WIR, storage, parser implementation, or other migration-only details without an intentional long-term Workshop-domain contract.
• Keep a public surface only when its semantics are intentionally supported independently of its historical implementation role.
• Preserve genuinely useful domain-oriented aliases when removing them would only create churn without reducing accidental contract surface.
• Keep internal storage and implementation freedom behind the public Program and domain APIs.
• Keep public API documentation aligned with the actual exported 1.x candidate surface.

Non-goals

• Preserving consumer builds across this pre-1.0 breaking change.
• Migrating Wright, OPY, or DEL/OSTW consumers inside this repository.
• Removing every re-export or alias for aesthetic consistency.
• Rewriting WIR or parser/emitter internals.
• Creating a second public compatibility layer to replace the first one.
• Moving OPY, DEL/OSTW, or Wright-specific semantics into workshop-rs.

Acceptance criteria

• The current public facade/export inventory matches live code.
• Every remaining public item has an intentional durable 1.x purpose; migration-only or implementation-shaped facades are no longer ordinary public API.
• Ordinary consumers do not need WIR arena/storage identities or parser implementation modules to use the supported Workshop API.
• No replacement abstraction is added unless a concrete supported Workshop-domain contract requires it.
• Public API documentation describes the actual retained surface and does not list retired compatibility paths as public.
• Existing public API, semantic, compatibility, and real-project tests remain meaningful and pass.

Dependencies / ownership

• Parent: Freeze the workshop-rs public API for 1.0 #252.
• Owner: workshop-rs for its public exports and compatibility promises.
• Wright, OPY, and DEL/OSTW own their migrations when adopting the breaking workshop-rs release.
• Consumer migration is not a blocker for removing compatibility-only owner APIs before 1.0.