fix: add version to health endpoint + warn users with stale compose files

Repo migration in March 2026 rewrote all commit hashes, leaving old
clones with a docker-compose.yml that builds from source instead of
pulling pre-built images.  Added detection warnings to compose.sh,
start.bat, and start.sh so affected users see clear instructions.
Also exposes APP_VERSION in /api/health for easier debugging.

backend/main.py

@@ -12,6 +12,8 @@ from dataclasses import dataclass, field
 from typing import Any
 from json import JSONDecodeError
 
+APP_VERSION = "0.9.6"
+
 logging.basicConfig(level=logging.INFO)
 logger = logging.getLogger(__name__)
 _start_time = time.time()
@@ -6667,6 +6669,7 @@ async def health_check(request: Request):
     last = d.get("last_updated")
     return {
         "status": "ok",
+        "version": APP_VERSION,
         "last_updated": last,
         "sources": {
             "flights": len(d.get("commercial_flights", [])),

backend/services/schemas.py

@@ -4,6 +4,7 @@ from typing import Optional, Dict, List, Any
 
 class HealthResponse(BaseModel):
     status: str
+    version: str = ""
     last_updated: Optional[str] = None
     sources: Dict[str, int]
     freshness: Dict[str, str]