Issue Description

The repository needs orchestration workflows that call reusable workflows to provide comprehensive PR validation and main branch protection.

Additional Context

Files to add:

• .github/workflows/pr-validation.yml - Comprehensive PR validation workflow calling all validation and security reusable workflows
• .github/workflows/main.yml - Main branch protection workflow with same checks as PR validation

Priority: Wave 4 (Priority 4) - Final integration, depends on all previous waves

Dependencies: Requires all reusable workflows from Issues #14 and #15

Testing: Create test PR, verify all validation workflows execute, check main branch protection triggers appropriately