feat(pa): add persistent FP8 decode path (#454)

* feat(pa): add persistent-scheduling FP8 decode path

Add the persistent-scheduling FP8 paged-attention kernel and a PS-focused regression harness so split-reduce behavior can be exercised against the Gluon reference.

Signed-off-by: sixifang <sixifang@amd.com>
Made-with: Cursor
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Signed-off-by: sixifang <sixifang@amd.com>
Co-authored-by: sixifang <sixifang@amd.com>
Co-authored-by: felix <felix.li@amd.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: 4 people