Adds the discriminator Sami specced (thread 5b46582e): the escape counter is
pure rendered rowMove and residual is |aboveShift|, so neither can recover the
grow-vs-shrink topology that decides the fix. Thread signed aboveShift (rAF path)
/ signed drift (RO path) through the correction probe as a diagnostic-only
'signedShift' field alongside wouldFire; production behavior unchanged.
The slow-scroll classifier joins each reversal to the correction attempt(s) in
its frame window (append-count join, order-robust across the two rAF loops) and
classifies: SKIP (gate/xcheck suppressed the write -> uncorrected reflow),
GROW (fired, signedShift>0 -> write is the felt snap, absorption's topology),
SHRINK (fired, signedShift<0 -> reflow renders it pre-write, only smaller
per-frame realization helps). Bumps ANCHOR_BUILD_STAMP to w4a-classifier-1 so the
stale-dist guard rejects any bundle missing signedShift.
Co-authored-by: Tyler Longwell <tlongwell@block.xyz>
Signed-off-by: Tyler Longwell <tlongwell@block.xyz>
