Point email links at conchecker.scoutitsystems.com and show build SHA in header.

APP_BASE_URL default (config, .env.example, both compose files) is now
https://conchecker.scoutitsystems.com with no port, so review-required
and final-report email links use the public site. CI bakes the short
commit SHA into the image as APP_BUILD via a Docker build-arg; /health
returns version+build and the site header shows the build so it's easy
to confirm which image is deployed. Local runs default to 'dev'.

backend/main.py

@@ -35,6 +35,8 @@ _FRONTEND_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "
 @app.get("/health")
 def health():
     return {"status": "ok", "model": config.MODEL,
+            "version": config.APP_VERSION,
+            "build": config.APP_BUILD,
             "key_configured": bool(config.AI_API_KEY),
             "email_configured": bool(config.SMTP_HOST and config.SMTP_USER and config.SMTP_PASSWORD)}