chore: bootstrap repository with governance docs

Initialize git, add Apache-2.0 LICENSE, .gitattributes (LF line
endings), AGENTS.md (entry points, stack, discovery order, baseline
checks), RUNBOOK.md (dev boot, prod deploy with overlay, ingestion,
failures, rollback, scaling notes), .env.prod.example with rotated
credential placeholders, and dev-only warnings on .env.example.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/main.py

@@ -0,0 +1,52 @@
+"""FastAPI entrypoint."""
+
+from __future__ import annotations
+
+from contextlib import asynccontextmanager
+from typing import AsyncIterator
+
+from fastapi import FastAPI
+
+from app import __version__
+from app.api import routes_health, routes_ingestion, routes_search
+from app.config import settings
+from app.logging_config import configure_logging, get_logger
+
+configure_logging()
+logger = get_logger(__name__)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI) -> AsyncIterator[None]:
+    logger.info("api.startup", version=__version__, prefix=settings.app_api_prefix)
+    # Best-effort bootstrap of MinIO buckets - non-fatal if it fails (health will reflect).
+    try:
+        from app.storage.minio_client import get_storage
+
+        get_storage().ensure_buckets()
+    except Exception as exc:  # noqa: BLE001
+        logger.warning("api.startup.minio_bootstrap_failed", error=str(exc))
+    yield
+    logger.info("api.shutdown")
+
+
+app = FastAPI(
+    title="LegacyHUB",
+    description="Hybrid lexical + semantic search over legacy PDF archives",
+    version=__version__,
+    lifespan=lifespan,
+)
+
+app.include_router(routes_health.router, prefix=settings.app_api_prefix)
+app.include_router(routes_ingestion.router, prefix=settings.app_api_prefix)
+app.include_router(routes_search.router, prefix=settings.app_api_prefix)
+
+
+@app.get("/")
+def root() -> dict[str, str]:
+    return {
+        "service": "LegacyHUB",
+        "version": __version__,
+        "api": settings.app_api_prefix,
+        "docs": "/docs",
+    }