Delete associated files when proof or campaign is deleted

Previously, deleting a proof or campaign only removed database records,
leaving orphaned files in the storage directory. Now the delete endpoints
extract file_storage_key from proof versions and delete files via
storage_service before removing database records.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/api/routes.py

@@ -31,6 +31,7 @@ from app.repositories import (
     AuditRepository,
     DropdownRepository,
 )
+from app.services.storage_service import storage_service
 
 router = APIRouter()
 
@@ -192,12 +193,23 @@ async def delete_campaign(
     db: AsyncSession = Depends(get_db),
     user: dict = Depends(get_current_user),
 ):
-    """Delete a campaign."""
+    """Delete a campaign and all associated files."""
     repo = CampaignRepository(db)
-    success = await repo.delete(campaign_id)
-    if not success:
+
+    # Get campaign with proofs and versions to extract file keys
+    campaign = await repo.get_by_id(campaign_id)
+    if not campaign:
         raise HTTPException(status_code=404, detail="Campaign not found")
 
+    # Delete files from storage for all proofs
+    for proof in campaign.proofs:
+        for version in proof.versions:
+            if version.file_storage_key:
+                await storage_service.delete_file(version.file_storage_key)
+
+    # Delete database records (cascades to proofs and versions)
+    await repo.delete(campaign_id)
+
 
 # Proof endpoints
 @router.get("/campaigns/{campaign_id}/proofs", response_model=list[ProofResponse])
@@ -279,12 +291,22 @@ async def delete_proof(
     db: AsyncSession = Depends(get_db),
     user: dict = Depends(get_current_user),
 ):
-    """Delete a proof."""
+    """Delete a proof and its associated files."""
     repo = ProofRepository(db)
-    success = await repo.delete(proof_id)
-    if not success:
+
+    # Get proof with versions to extract file keys
+    proof = await repo.get_by_id(proof_id)
+    if not proof:
         raise HTTPException(status_code=404, detail="Proof not found")
 
+    # Delete files from storage
+    for version in proof.versions:
+        if version.file_storage_key:
+            await storage_service.delete_file(version.file_storage_key)
+
+    # Delete database records
+    await repo.delete(proof_id)
+
 
 # Audit endpoints
 @router.post("/proofs/{proof_id}/versions/{version}/flag", response_model=FlaggedItemResponse, status_code=201)