ci: track repository Project support files #12

Context

base-platform-tools already tracks the issue-branch policy workflow, but the checkout contains untracked Base Project support files. The local Project Intake workflow is an older generated version and differs from the current Base template.

Change

• track .github/base-project.yml;
• replace the stale .github/workflows/project-intake.yml with the current Base template;
• extend the repository validation to require these support files if appropriate.

Validation

Run tests/validate.sh, validate YAML and shell syntax, and inspect the staged paths and whitespace.