What

Prepare common_system for a stable v1.0 release. This is the foundation library (Tier 0) and must stabilize first before downstream libraries can release their v1.0.

• Current version: 0.2.0
• Test coverage: 80%+
• API stability: High (interface-only)

Part of #639

Why

• Downstream libraries (thread_system, container_system, etc.) depend on common_system
• Must provide stable API guarantees before any dependent library can reach v1.0
• Pre-1.0 status discourages external adoption

How

v1.0 Readiness Checklist

• API freeze audit: Review all public headers — no breaking changes allowed after freeze
• Result<T> migration: Verify zero throw in public APIs (use result_t consistently)
• CMake exports: Stable target name common_system::common_system with proper config
• Test coverage: Verify 70%+ maintained (currently 80%+)
• Deprecation cleanup: Remove any deprecated APIs
• Documentation: Complete API reference and migration guide from 0.x
• CHANGELOG: Ensure keep-a-changelog format, document all breaking changes from 0.x
• Semantic versioning: Tag v1.0.0 release

Acceptance Criteria

• All public API headers reviewed and frozen
• No throw statements in public API paths
• CMake find_package(common_system) works cleanly
• Full test suite passes
• README documents v1.0 API guarantees
• CHANGELOG covers 0.x → 1.0 migration