Add architecture decision records for major workflow choices

[coisa]

Objective

Add architecture decision records (ADRs) for major DevTools workflow and synchronization choices.

Current Limitation

The project has accumulated important design decisions around sync behavior, workflow previews, wiki submodules, Pages deployments, and preservation of consumer customizations. These decisions are visible in code and workflows but not captured as durable architectural context.

Proposed Work

Introduce an ADR structure and add initial records for major current decisions.

Scope

• Add an ADR index under docs/internals or docs/architecture.
• Document the ADR format used by the project.
• Add initial ADRs for:
  • wiki PR preview branches and post-merge publishing;
  • reports previews and Pages deployment strategy;
  • sync preserving consumer customizations by default;
  • generated resource stubs versus reusable workflows.
• Link ADRs from architecture or advanced docs.

Non-goals

• Rewriting existing architecture docs.
• Creating ADRs for every historical commit.
• Changing implementation behavior.

Acceptance Criteria

Delivery Criteria

• An ADR index exists in the documentation tree.
• At least four initial ADRs capture current major workflow/sync decisions.
• ADRs include context, decision, consequences, and status.
• Existing architecture docs link to the ADR index.
• Documentation builds successfully.

Architectural / Isolation Criteria

• ADRs are concise and avoid duplicating implementation details from workflow files.
• The chosen ADR location and naming convention can scale to future records.