Add Power BI reporting endpoints — flat tabular data via API key auth

Three read-only endpoints under /reporting/:
- /hotels       hotel dimension table (tier, stars, review score)
- /rates        full rates fact — all sources, room types, scrape history in one flat table
- /occupancy    Newbook occupancy per date × room category

Rates UNION covers Booking.com scrapes, direct competitor engines (with
configured room/rate labels), and own hotel Newbook headline rates.
Authenticated via X-API-Key header; key stored in system_config.reporting_api_key.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/main.py

@@ -3,6 +3,8 @@ Rate Monitor — FastAPI Backend
 """
 import logging
 import sys
+import os
+import time
 from contextlib import asynccontextmanager
 
 logging.basicConfig(
@@ -15,7 +17,7 @@ from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
 from database import DATABASE_URL
-from api import bookability, competitors, analysis, direct
+from api import bookability, competitors, analysis, direct, reporting
 from scheduler import start_scheduler, shutdown_scheduler
 
 
@@ -60,6 +62,7 @@ app = FastAPI(
     version="1.0.0",
     lifespan=lifespan,
 )
+STARTED_AT = str(int(time.time() * 1000))
 
 app.add_middleware(
     CORSMiddleware,
@@ -73,8 +76,9 @@ app.include_router(bookability.router,  prefix="/bookability",       tags=["Book
 app.include_router(competitors.router,  prefix="/competitors",       tags=["Competitors"])
 app.include_router(analysis.router,     prefix="/analysis",          tags=["Rate Analysis"])
 app.include_router(direct.router,       prefix="/direct",            tags=["Direct Rates"])
+app.include_router(reporting.router,    prefix="/reporting",         tags=["Reporting"])
 
 
 @app.get("/health")
 async def health_check():
-    return {"status": "healthy", "service": "rate-monitor-api"}
+    return {"status": "healthy", "service": "rate-monitor-api", "version": os.environ.get("BUILD_VERSION", STARTED_AT)}