fix: dynamic TracedRepository proxy + disable tracing in test suite

Replace brittle explicit method-by-method proxy with __getattr__-based
dynamic proxy that forwards all args/kwargs to the inner repo. Fixes
TypeError on get_logs_after_id() where concrete repo accepts extra
kwargs beyond the ABC signature.

Pin DECNET_DEVELOPER_TRACING=false in conftest.py so .env.local
settings don't leak into the test suite.

tests/conftest.py

@@ -9,6 +9,7 @@ import os
 os.environ["DECNET_JWT_SECRET"] = "stable-test-secret-key-at-least-32-chars-long"
 os.environ["DECNET_ADMIN_PASSWORD"] = "test-password-123"
 os.environ["DECNET_DEVELOPER"] = "true"
+os.environ["DECNET_DEVELOPER_TRACING"] = "false"
 os.environ["DECNET_DB_TYPE"] = "sqlite"
 
 import pytest