Route public Workshop operations through the canonical Program API

[Teakowa]

Parent: #112
Depends on: #177, #178

Goal

Make the canonical public Program API the shared boundary for raw parsing, validation/analysis, conversion/editing, emission, and the CLI, then retire accidental compatibility/storage exposure before the 1.0 freeze.

Scope

• Make raw Workshop parsing produce the canonical public Program model.
• Make validation, Workshop-owned analysis, conversion/source-aware editing, and emission consume that same public model.
• Keep workshop-rs-cli on the ordinary public library boundary.
• Audit crate/module visibility and remove or explicitly classify compatibility re-exports, arena/storage surfaces, generator/catalog-authoring tables, census/test support, and CLI helper modules that are not intended 1.0 contracts.
• Review public error/category/source access needed by machine consumers under the canonical API.
• Add concise public documentation showing both raw Workshop parse/emit use and independent-language construction/lowering into the same Program model.

Non-goals

• Rewriting parser/emitter algorithms for style or file size.
• Consumer-specific OPY/DEL/Wright migration.
• Enabling the post-1.0 semver gate before the candidate surface is accepted.
• Unrelated repository cleanup.

Acceptance criteria

• Parse, validate/analyze, edit/convert, and emit operate through one public Program contract.
• The CLI does not depend on privileged private or compatibility-only library surfaces.
• Ordinary crate navigation is organized around Workshop concepts and operations rather than repository extraction history.
• Storage/generator/test-support APIs are no longer accidentally frozen as ordinary public contracts.
• Public docs demonstrate the canonical program model without requiring knowledge of WIR storage internals.