Refactor to async TimescaleDB backend & add Alembic migrations

db_async.py

@@ -0,0 +1,57 @@
+import os
+import sqlalchemy
+from databases import Database
+from sqlalchemy import MetaData, Table, Column, Integer, String, Float, DateTime
+
+# Environment: Postgres/TimescaleDB connection URL
+DATABASE_URL = os.getenv("DATABASE_URL", "postgresql://postgres:password@localhost:5432/dereth")
+# Async database client
+database = Database(DATABASE_URL)
+# Metadata for SQLAlchemy Core
+metadata = MetaData()
+
+# Telemetry events hypertable schema
+telemetry_events = Table(
+    "telemetry_events",
+    metadata,
+    Column("id", Integer, primary_key=True),
+    Column("character_name", String, nullable=False),
+    Column("char_tag", String, nullable=True),
+    Column("session_id", String, nullable=False, index=True),
+    Column("timestamp", DateTime(timezone=True), nullable=False, index=True),
+    Column("ew", Float, nullable=False),
+    Column("ns", Float, nullable=False),
+    Column("z", Float, nullable=False),
+    Column("kills", Integer, nullable=False),
+    Column("kills_per_hour", Float, nullable=True),
+    Column("onlinetime", String, nullable=True),
+    Column("deaths", Integer, nullable=False),
+    Column("rares_found", Integer, nullable=False),
+    Column("prismatic_taper_count", Integer, nullable=False),
+    Column("vt_state", String, nullable=True),
+    # New telemetry metrics
+    Column("mem_mb", Float, nullable=True),
+    Column("cpu_pct", Float, nullable=True),
+    Column("mem_handles", Integer, nullable=True),
+    Column("latency_ms", Float, nullable=True),
+)
+
+# Persistent kill statistics per character
+char_stats = Table(
+    "char_stats",
+    metadata,
+    Column("character_name", String, primary_key=True),
+    Column("total_kills", Integer, nullable=False, default=0),
+)
+
+async def init_db_async():
+    """Create tables and enable TimescaleDB hypertable for telemetry_events."""
+    # Create tables in Postgres
+    engine = sqlalchemy.create_engine(DATABASE_URL)
+    metadata.create_all(engine)
+    # Enable TimescaleDB extension and convert telemetry_events to hypertable
+    with engine.connect() as conn:
+        conn.execute("CREATE EXTENSION IF NOT EXISTS timescaledb;")
+        conn.execute(
+            "SELECT create_hypertable('telemetry_events', 'timestamp', if_not_exists => true);"
+        )