docs: rewrite README for the working system + CHANGELOG; bump to 0.2.0

README was a pre-MVP stub (wrong, said set an Anthropic key). Now documents the
real system: two-layer architecture, role-based backends, memory tiers + dream
cycle, poker copilot (sessions/hands/villains/equity/recaps), web pages, ratings,
and how to run it as services. Added CHANGELOG with the 0.2.0 feature set. Legacy
v0.6.x design docs kept in docs/ as history.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "lyra"
-version = "0.1.0"
+version = "0.2.0"
 description = "Persistent, autonomous AI assistant"
 readme = "README.md"
 requires-python = ">=3.11"