chore: add CODEOWNERS for maintainer review on critical paths (#36)

Adds CODEOWNERS to automatically request @TommiLindfors review on PRs
touching critical paths:

- **Protected**: schemas, workflows, scenarios, scripts, CI, governance,
methodology
- **Open for contributors**: source records, tasks, deadlines, document
requirements, institutions, conditions

This pairs with the new branch protection (1 required review) to ensure
maintainer oversight on structural changes while keeping data
contributions easy.

Author: TommiLindfors

.github/CODEOWNERS

@@ -0,0 +1,24 @@
+# CODEOWNERS - workflow-data
+# These owners are automatically requested for review on PRs
+# that modify the matching paths.
+
+# Schemas define the data model - changes here affect all data files
+/schemas/                   @TommiLindfors
+
+# Workflows define the core bereavement process sequences
+/data/workflows/            @TommiLindfors
+
+# Scenarios define how workflows are composed
+/data/scenarios/            @TommiLindfors
+
+# Validation and export scripts
+/scripts/                   @TommiLindfors
+
+# CI/CD configuration
+/.github/                   @TommiLindfors
+
+# Governance and methodology
+/GOVERNANCE.md              @TommiLindfors
+/METHODOLOGY.md             @TommiLindfors
+/REUSE.toml                 @TommiLindfors
+/datapackage.json           @TommiLindfors