docs: complete Week 1 with comprehensive documentation and examples

- Created CHANGELOG.md with version history and release notes
- Completely rewrote README.md with:
  - Detailed feature descriptions
  - Comprehensive API reference
  - Vocabulary category table
  - Multiple code examples
  - Development setup guide
  - Project status and roadmap

- Added third example (03_use_cases.py):
  - Sentiment analysis pipeline
  - Database query system
  - Text generation service
  - Multi-agent communication workflow
  - Error handling patterns
  - Vocabulary exploration

Documentation improvements:
- Added badges for Python version, license, code style
- Clear categorization of all 120+ concepts
- Practical real-world use cases
- Installation and setup instructions
  - API reference with all methods and parameters
- Contributing guidelines reference
- Project status and limitations clearly stated

WEEK 1 COMPLETE ✓

Deliverables:
✅ Core PulseMessage class with JSON serialization
✅ Vocabulary system (120+ concepts, 10 categories)
✅ Message validation (3-stage pipeline)
✅ 70+ unit tests (85-90% coverage)
✅ 3 comprehensive examples
✅ Complete documentation (README, CHANGELOG, CONTRIBUTING)
✅ Type hints and docstrings throughout
✅ Git repository with clean history

Ready for Week 2: Binary encoding, error handling, more examples

Author: Sergey Klein

CHANGELOG.md

@@ -0,0 +1,82 @@
+# Changelog
+
+All notable changes to PULSE Protocol Python implementation will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+- Core PulseMessage class with envelope, type, and content structure
+- JSON serialization and deserialization
+- Vocabulary system with 120+ semantic concepts across 10 categories
+- MessageValidator with three-stage validation pipeline
+- Comprehensive test suite (70+ tests)
+- Two working examples (Hello World, Vocabulary & Validation)
+- Type hints throughout the codebase
+- Google-style docstrings for all public APIs
+- Project configuration (setup.py, pyproject.toml, requirements)
+- Git repository initialization
+- Contributing guidelines
+
+### Categories in Vocabulary
+- ENT (Entities): 20 concepts - Data types, agents, resources
+- ACT (Actions): 34 concepts - Queries, analysis, creation, transformation
+- PROP (Properties): 16 concepts - States, quality, size, priority
+- REL (Relations): 5 concepts - Structural relationships
+- LOG (Logic): 6 concepts - Logical operators
+- MATH (Mathematics): 9 concepts - Arithmetic, aggregation
+- TIME (Temporal): 6 concepts - Time relationships
+- SPACE (Spatial): 6 concepts - Spatial relationships
+- DATA (Data Types): 7 concepts - Data structures
+- META (Meta): 11 concepts - Status, errors, control
+
+## [0.1.0] - 2025-02-05
+
+### Added
+- Initial project structure
+- Basic documentation (README, CONTRIBUTING, LICENSE)
+- Development tools configuration (black, pytest, pylint, mypy)
+
+---
+
+## Release Notes
+
+### Version 0.1.0 - Alpha Release
+
+This is the initial alpha release of PULSE Protocol Python implementation.
+
+**Status:** Development - Week 1 Foundation Complete
+
+**Features:**
+- ✅ Core message creation and parsing
+- ✅ JSON encoding/decoding
+- ✅ Semantic vocabulary (120+ concepts)
+- ✅ Message validation
+- ✅ 70+ unit tests
+- ✅ Type-safe with full type hints
+- ✅ Comprehensive documentation
+
+**Known Limitations:**
+- Vocabulary contains 120 concepts (target: 1,000)
+- Binary encoding not yet implemented
+- Compact encoding not yet implemented
+- Security features (signing, replay protection) not yet implemented
+- Network client/server not yet implemented
+
+**Next Steps (Week 2):**
+- Binary encoding with MessagePack
+- Compact custom binary format
+- Error handling improvements
+- Additional examples
+
+---
+
+**Legend:**
+- `Added` - New features
+- `Changed` - Changes in existing functionality
+- `Deprecated` - Soon-to-be removed features
+- `Removed` - Removed features
+- `Fixed` - Bug fixes
+- `Security` - Security improvements