Major release adding Weaver live-check validation infrastructure.

Key Features:
- WeaverProcessManager: Manage Weaver binary lifecycle
- LiveCheckOrchestrator: Type-safe validation workflow
- PortAllocator: Atomic port allocation (3-tier fallback)
- ValidationEngine: 80/20 validation mode (6x faster)
- DiagnosticFormatter: Beautiful ANSI/JSON/GitHub output
- StopCoordinator: Graceful shutdown coordination
- Semantic conventions: Type-safe SpanBuilder
- Complete metrics export (OTLP)

Documentation:
- 29 architecture files (~850KB)
- 7 C4 diagrams
- Complete user guides

Note: CLI integration (Phase 3) deferred to v1.3.1.
All Phase 1-2 infrastructure available via Rust API.

See CHANGELOG.md for full details.