docs: comprehensive usage guide + README badge updates

- docs/USAGE.md: complete user-facing documentation covering:
  - Installation (basic, extras, Rust backend)
  - Quick start (route, compress, remember/recall, step)
  - Core API reference with examples
  - Enterprise features: tenancy, schema validation, rate limiting,
    config management, encryption, JWT auth, TTL, health probes, backup/restore
  - Observability: telemetry, Prometheus, OpenTelemetry, JSONL export
  - Security: pentest command + hardening checklist
  - Deployment: blue-green markers, load testing, chaos engineering
  - Testing commands

- README.md: updated version badge 0.3.0→0.5.0, tests 15→135,
  added link to docs/USAGE.md

Verification: 135/135 tests passing, ruff 0, mypy 0

Author: DJLougen

README.md

@@ -2,9 +2,9 @@
 
 **Orchestration layer for AI agents** - CPU-side routing, context compression, and causal memory to reduce token usage by 64%.
 
-[![Version](https://img.shields.io/badge/version-0.3.0-blue)](https://github.com/DJLougen/hive)
+[![Version](https://img.shields.io/badge/version-0.5.0-blue)](https://github.com/DJLougen/hive)
 [![Python](https://img.shields.io/badge/python-3.10+-green)](https://python.org)
-[![Tests](https://img.shields.io/badge/tests-15%20passed-brightgreen)](https://github.com/DJLougen/hive/actions)
+[![Tests](https://img.shields.io/badge/tests-135%20passed-brightgreen)](https://github.com/DJLougen/hive/actions)
 [![License](https://img.shields.io/badge/license-MIT-yellow)](https://opensource.org/licenses/MIT)
 [![RTX 3090](https://img.shields.io/badge/RTX%203090-validated-orange)]()
 [![DGX Spark](https://img.shields.io/badge/DGX%20Spark-validated-red)]()
@@ -89,6 +89,8 @@ pip install -e ".[dev]"
 
 ## Quick Start
 
+📖 **Full usage guide**: [docs/USAGE.md](docs/USAGE.md) — covers enterprise features, security, deployment, and observability.
+
 ```python
 from hive import HiveStack