Complete OPY directive and preprocessing semantics before Workshop integration

[Teakowa]

Parent: #7

Goal

Finish the source-language directive and preprocessing behavior that opy-rs can own before Workshop lowering, while keeping target-specific effects explicitly deferred.

Context

The support matrix still has planned coverage for advanced preprocessing directives, translations, and optimization controls. Some of these have frontend-visible semantics that belong in opy-rs; their Workshop emission/optimizer/localization effects do not.

Scope

• Implement #!mainFile and #!allowMacroRedeclaration behavior where supported by the pinned reference.
• Implement inventory-backed #!rulePrefix* behavior and other preprocessing-state directives that affect OPY source interpretation before lowering.
• Recognize, validate, preserve provenance for, and expose semantic state for #!translations without duplicating Workshop locale/catalog data.
• Recognize, validate, and track the #!optimize* / #!replace0By* family and related compression controls as frontend directive state when their backend effects cannot yet execute.
• Complete evidence-backed rule annotation forms currently outside the declared subset (@Team/@Slot arguments, @Name, @Hero, @Disabled, @Delimiter, @NewPage, @SuppressWarnings) where these are source-language semantics rather than Workshop catalog content.
• Split mixed support-matrix rows where necessary so frontend recognition/state and Workshop-dependent backend effects are not represented by one ambiguous status.
• Add positive/negative fixtures and oracle probes for directive scope, duplicate/redeclaration behavior, malformed forms, and cross-file interactions.

Non-goals

• Implementing Workshop optimizer transformations merely to match upstream output form.
• Localized Workshop emission or locale catalog ownership.
• Adding Workshop settings/content tables.
• Starting OPY→Workshop lowering.

Acceptance criteria

• All advanced directive/preprocessing behavior that is observable before Workshop lowering is parsed, validated, and represented with corpus/probe evidence.
• Backend-only optimization/localization/emission effects remain explicitly lowering-dependent rather than being approximated.
• Support-matrix rows no longer conflate frontend directive support with backend execution semantics.
• Unsupported/reference-rejected directive forms fail with structured diagnostics and source provenance.
• Existing preprocessing, macro/runtime, tooling, and differential tests remain green.
• No Workshop catalog/locale data or workshop-rs dependency is introduced.