per-campaign settings, default campaign folders, custom prompt fix

backend/app/config.py

@@ -31,16 +31,15 @@ def campaign_notes_dir(campaign_id: str) -> Path:
 for d in (UPLOAD_DIR, AUDIO_DIR, TRANSCRIPT_DIR, NOTES_DIR):
     d.mkdir(parents=True, exist_ok=True)
 
-# Runtime-editable settings (stored in DB, these are just first-run defaults).
-# NOTE: this flat key/value schema is the single source of truth for settings -
-# it's what every consumer (pipeline/summarize.py, pipeline/transcribe.py,
-# routers/models.py, routers/diagnostics.py) actually reads. The settings
-# router and frontend must mirror these exact keys - a nested schema would
-# silently disconnect the Settings/Setup UI from the pipeline.
-DEFAULT_SETTINGS = {
-    # Onboarding
+# Runtime-editable global settings (stored in the `settings` table).
+# Only onboarding state lives here; everything else is per-campaign.
+GLOBAL_SETTINGS = {
     "onboarding_completed": "false",
+}
 
+# Per-campaign settings — seeded into campaign_settings on creation.
+# Every layer (frontend, router, pipeline) reads these from the campaign.
+CAMPAIGN_SETTINGS = {
     # Transcription
     "whisper_model": "medium",       # tiny|base|small|medium|large-v3 - user picks based on their hardware
     "whisper_compute_type": "int8",