Fix render_effect to find uploads in new cache location

The legacy render_effect task was looking for inputs only at
CACHE_DIR/{hash}, but uploads now go through cache_manager which
stores them in CACHE_DIR/nodes/{node_id}/. Now uses
cache_manager.get_by_content_hash() which checks both locations.

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

tasks.py

@@ -154,8 +154,7 @@ def render_effect(self, input_hash: str, effect_name: str, output_name: str) ->
     Returns:
         Provenance record with output hash
     """
-    # Cache directory (shared between server and worker)
-    CACHE_DIR = Path(os.environ.get("CACHE_DIR", str(Path.home() / ".artdag" / "cache")))
+    from cache_manager import get_cache_manager
 
     # Registry hashes (for effects/infra metadata only)
     REGISTRY = {
@@ -173,9 +172,10 @@ def render_effect(self, input_hash: str, effect_name: str, output_name: str) ->
         }
     }
 
-    # Input comes from cache by hash
-    input_path = CACHE_DIR / input_hash
-    if not input_path.exists():
+    # Input comes from cache by hash (supports both legacy and new cache locations)
+    cache_manager = get_cache_manager()
+    input_path = cache_manager.get_by_content_hash(input_hash)
+    if not input_path or not input_path.exists():
         raise ValueError(f"Input not in cache: {input_hash}")
 
     output_dir = CACHE_DIR