fix: env var overrides for campaign settings (hf_token, ollama_host etc)

backend/app/routers/sessions.py

@@ -6,6 +6,7 @@ from pathlib import Path
 from fastapi import APIRouter, UploadFile, File, Form, HTTPException
 
 from .. import database as db, config, jobs
+from ..config import merge_campaign_settings_with_env
 from ..errors import PipelineError
 from ..pipeline.audio import extract_audio
 from ..pipeline.transcribe import transcribe_and_diarize
@@ -86,7 +87,7 @@ def get_session(session_id: str):
 
 def _run_transcription(session_id: str, video_path: Path, audio_path: Path, transcript_path: Path, campaign_id: str | None = None):
     cid = campaign_id or "default"
-    settings = db.get_campaign_settings(cid)
+    settings = merge_campaign_settings_with_env(db.get_campaign_settings(cid))
 
     def run(progress_cb):
         db.get_conn()  # ensure thread-local connection exists in this worker thread