Authoring workflow definitions

## Context

Part of [Epic #732](https://github.com/adobe/spectrum-design-data/issues/732) — Phase 4: Output generators and authoring app integration.

Before building the authoring app UI, we need structured workflow documents that formalize the git-based editing model. These serve as both requirements and input for wireframe generation.

## Goal

Produce a set of Markdown workflow documents in `docs/authoring-app/workflows/` that define every user-facing editing operation with enough precision to generate wireframes and derive validation rules.

## Workflows to define

- **Create token** — new token with name object, value, UUID, optional dimensions
- **Edit token value** — change value for specific dimension context
- **Deprecate token** — set `deprecated` version, `deprecated_comment`, `replaced_by`, optional `plannedRemoval`
- **Rename token** — new name object + `replaced_by` on old token (or just new UUID assignment)
- **Add dimension variant** — add `colorScheme=dark` variant of existing token
- **Bulk operations** — deprecate/rename a batch of tokens (layout consolidation pattern)
- **Review changes** — diff preview before PR creation
- **Resolve validation errors** — real-time SPEC rule feedback during editing

## Each workflow document must include

- Preconditions (what state the data must be in)
- Steps (user actions + system responses)
- Postconditions (what the data looks like after)
- Validation constraints (which SPEC rules apply)
- Git operations (branch, commit, PR)

## Acceptance criteria

- All 8 workflows documented in `docs/authoring-app/workflows/`
- Each document follows the standard structure above
- SPEC rule references are accurate (SPEC-001 through SPEC-013)

Create the eight Markdown workflow documents in docs/authoring-app/workflows/. Start by reviewing SPEC-001 through SPEC-013 and the required preconditions, steps, postconditions, validation constraints, and Git operations for each workflow. Done means all eight editing operations are documented with accurate SPEC references and the standard structure.

Written by the indexing model from the issue text.