Fix Settings-saved API keys never actually being used

Every *_API_KEY was read from the env var once at startup and never
checked against settings.json again, so saving a new key on the
Settings page updated the file but had zero effect on real requests —
reported live as "SABnzbd rejected the API key" right after rotating
and saving a new one there. A saved key now overrides the .env value
at startup, matching what the Settings page's own toast already says
("restart the container to apply").

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app.py

@@ -164,6 +164,17 @@ OMBI_PORT = os.environ.get("OMBI_PORT", "3579")
 OMBI_URL = f"http://{OMBI_HOST}:{OMBI_PORT}"
 OMBI_API_KEY = os.environ.get("OMBI_API_KEY", "")
 
+# A key saved via the Settings page lives in settings.json and must win over
+# the .env value here — otherwise "Save" on that page silently does nothing
+# for anything that actually calls out to the service.
+_saved_settings = load_settings()
+SONARR_API_KEY   = _saved_settings.get("sonarr_api_key")   or SONARR_API_KEY
+RADARR_API_KEY   = _saved_settings.get("radarr_api_key")   or RADARR_API_KEY
+SABNZBD_API_KEY  = _saved_settings.get("sabnzbd_api_key")  or SABNZBD_API_KEY
+TAUTULLI_API_KEY = _saved_settings.get("tautulli_api_key") or TAUTULLI_API_KEY
+PROWLARR_API_KEY = _saved_settings.get("prowlarr_api_key") or PROWLARR_API_KEY
+OMBI_API_KEY     = _saved_settings.get("ombi_api_key")     or OMBI_API_KEY
+
 RT_HEADERS = {
     "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
     "Accept-Language": "en-US,en;q=0.9",