Add PHILOSOPHY.md and refocus documentation structure

Created PHILOSOPHY.md to establish the foundational vision and
architectural patterns for the Tatlock system.

PHILOSOPHY.md:
- Establishes Tatlock as a homelab butler coordinating expert agents
- Defines the British household metaphor and two-tier architecture
- Documents the Steward (request analysis) and Butler (orchestration)
- Describes household staff roles (Handyman, Housekeeper, Secretary, Developer)
- Explains real-time reasoning transparency for UX
- Details model efficiency strategy (unified base model, specialized when needed)
- Sets modification policy: only update for architectural deviations

README.md:
- Streamlined header with link to PHILOSOPHY.md
- Simplified description to focus on practical usage
- Updated documentation section to prioritize PHILOSOPHY.md
- Maintained all usage examples and technical guides

AGENTS.md:
- Added prominent link to PHILOSOPHY.md at header
- Emphasized that development should align with philosophy

Documentation hierarchy:
1. PHILOSOPHY.md - Vision and architectural patterns (stable)
2. README.md - User guide and practical usage
3. AGENTS.md - LLM agent development guidelines
4. CHANGELOG.md - Version history

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

AGENTS.md

@@ -2,6 +2,8 @@
 
 This document contains instructions and documentation references for AI assistants working with this codebase.
 
+> **📖 Important**: Before working on this project, read [PHILOSOPHY.md](PHILOSOPHY.md) to understand the system vision, architectural patterns, and design goals. All development should work towards realizing those patterns.
+
 ## Project Overview
 
 This project implements an OpenAI-compatible API endpoint using FastAPI, with streaming support. Currently returns mock responses - infrastructure prepared for future Ollama/PydanticAI integration.