feat(backend): data model — identity / clinical / audit, repositories, create_all

Two DeclarativeBases on two engines (ADR-003): identity holds direct
identifiers, clinical holds token-keyed pseudonymised data plus audit_log.
Portable types (JSONB variant, tz-aware UTC timestamps rejecting naive
values) so tests run on SQLite. init_db() runs create_all at startup.
Guardrail #5 checked by AST and import-graph tests.

Refs #6

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/main.py

@@ -5,8 +5,11 @@ from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
 
 from fastapi import FastAPI
+from sqlalchemy.exc import SQLAlchemyError
 
 from app.config import get_settings
+from app.db.bootstrap import init_db
+from app.db.session import dispose
 
 # Logs carry only tokens, states and event codes — never PII or raw message text.
 logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(name)s %(message)s")
@@ -17,8 +20,16 @@ log = logging.getLogger("app")
 async def lifespan(_: FastAPI) -> AsyncGenerator[None, None]:
     settings = get_settings()
     log.info("startup llm_provider=%s demo_clock=%s", settings.llm_provider, settings.demo_clock)
-    # DB init (#6), scheduler (#13) and Telegram bot (#11) hook in here.
+    try:
+        await init_db()
+        log.info("db schema ready")
+    except (OSError, SQLAlchemyError) as exc:
+        # In compose Postgres is required and healthy before the app starts; this branch is for running the
+        # API (and its tests) without a database. Endpoints touching the DB will fail until it is reachable.
+        log.error("db init failed, continuing without db: %s", type(exc).__name__)
+    # Scheduler (#13) and Telegram bot (#11) hook in here.
     yield
+    await dispose()
 
 
 app = FastAPI(title="PTSRaiAgent API", version="0.1.0", lifespan=lifespan)