The dynamic VBAR cast path applied want_requant to both weights and biases.
For an FP8 checkpoint with a low-VRAM LoRA patch, this returned an FP8 bias
to the optimized linear operation even though the activation dtype was FP16.
Restrict the optional requantized return value to weights while preserving
resident-storage updates for both parameters. Make the legacy FP8 linear path
release its VBAR/offload resources in a finally block so backend failures do
not leave pages pinned before the normal fallback runs.
Add regressions for the weight/bias dtype contract and exception cleanup.
Fixes#14952
Signed-off-by: liminfei <liminfei@amd.com>
