feat(lora): log exact side-channel applies

The exact factor path was the only apply route with no log line; its
success read as silence. Track layers taking it beside the hosted and
fallback lists and report all three as key=value apply lines
(apply=exact/hosted/requantize); the stack fallback notices use the
same form. The suite pins its stack-mode baseline to sum so a mode
left set in user config cannot reroute tests that assume plain
summation.

test/test-sdnq-lora-factors.py

@@ -82,6 +82,7 @@ from sdnq.quantizer import sdnq_quantize_layer, SDNQConfig  # pylint: disable=wr
 
 DEVICE = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
 OUT_F, IN_F, RANK = 512, 512, 8
+shared.opts.lora_stack_mode = 'sum' # suite baseline regardless of user config; stack tests set modes via their own context managers
 
 results: dict[str, dict] = {}