feat(state): Implement State Schema for SEED Architecture (Issue #3)

- Add JSON schema at schemas/state.json with full validation rules
- Implement State, StateType, StateMetadata dataclasses in models/state.py
- Support immutable state objects with versioning and TTL
- Include serialization/deserialization (JSON and dict)
- Add next_version() for state history chaining
- Comprehensive test suite with 19 tests (100% pass)
- Full documentation at docs/state-schema.md

Features:
- UUID validation for all ID fields
- Optimistic locking via version numbers
- Flexible payload structure
- Metadata support (source, provenance, tags)
- Expiration checking via TTL
- Complete type hints

Closes Issue #3

README.md

@@ -1,3 +1,65 @@
-# electra-archon
+# Electra Archon
 
-Electra Archon - SEED Architecture Implementation
+SEED Architecture Implementation for the Electra Archon wizard.
+
+## SEED Architecture
+
+SEED stands for **S**tate-**E**vent-**E**ntity-**D**omain - a modular architecture for building resilient, auditable systems.
+
+### Components
+
+1. **State** - Immutable snapshots of entity state with versioning
+2. **Event** - Pub/sub system for inter-component communication
+3. **Entity** - Core domain objects with identity
+4. **Domain** - Business logic and rules
+
+## Project Structure
+
+```
+electra-archon/
+├── schemas/         # JSON schemas for data validation
+│   └── state.json   # State schema definition
+├── models/          # Python data models
+│   └── state.py     # State dataclass implementation
+├── docs/            # Documentation
+│   └── state-schema.md
+├── tests/           # Test suite
+│   └── test_state.py
+└── pytest.ini       # Test configuration
+```
+
+## Quick Start
+
+```python
+from models.state import State, StateType, StateMetadata
+import uuid
+
+# Create a state
+state = State.create(
+    entity_id=str(uuid.uuid4()),
+    state_type=StateType.ACTIVE,
+    payload={"status": "running"},
+    metadata=StateMetadata(source="electra", tags=["seed"])
+)
+
+# Serialize
+json_str = state.to_json()
+```
+
+## Running Tests
+
+```bash
+pytest tests/ -v
+```
+
+## Backlog
+
+See [Issues](http://143.198.27.163:3000/allegro/electra-archon/issues) for current backlog:
+
+- Issue #3: Design Electra State Schema for SEED Architecture ✅
+- Issue #4: Implement Event Bus for Inter-Archon Communication
+- Issue #5: Create Entity Resolution Service
+
+## License
+
+MIT