Phase 10: sprite session — runner, brute, shield zombie, weapon tin

Sheets generated with the existing zombie sheet as the style anchor (edit mode);
sliced to z_f1/2 (runner sprint), z_g1/2 (brute + net-post club), z_s1/2/3
(shield zombie, chair up / chair dropped stagger), x_tin (black new-balls tin).
assets/_slice.py is now committed (chroma-key + de-fringe + segmentation) so the
pipeline survives scratchpad wipes; HANDOFF updated.

Sprites are NOT wired into render.js yet — Phase 11 does that after Oliver
approves the sheets (plan's design checkpoint).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

HANDOFF.md

@@ -102,10 +102,14 @@ gives clean manual stepping. `T.press('Space')` = tap. Dismiss the intro overlay
   preview_start (a new port = new origin = cold cache). Always sanity-check a just-added
   field exists (e.g. `T.G.newField !== undefined`) before trusting test results.
 - Sprite pipeline: generate via generate-image skill (needs OPENROUTER_API_KEY in repo .env,
-  gitignored) → magenta background → scratchpad slice.py (chroma-key, segment, strip ground
-  lines/dividers, common-scale per sheet, IDLE_TARGET_H=112). Generator sometimes ignores
-  magenta (then: edit-mode the image back to magenta) or draws near-identical animation
-  frames (then: re-prompt with strongly contrasted pose descriptions).
+  gitignored; run the script with the scratchpad venv python — system python lacks requests)
+  → magenta background → assets/_slice.py (COMMITTED now, no more scratchpad rebuilds:
+  chroma-key on the corner color + magenta de-fringe, column-gap segmentation, --largest
+  keeps only the main blob, common-scale per sheet, IDLE_TARGET_H=112). Generator sometimes
+  ignores magenta (harmless — the key uses the corner color) or draws near-identical
+  animation frames (re-prompt with strongly contrasted pose descriptions). If two frames
+  touch (a dragged weapon bridging the gap), split the sheet at the midpoint and slice each
+  half with --largest. Passing the existing sheet as --input (edit mode) nails the style.
 - drawChar mirrors sprites by ch.facing — any stance that must not mirror needs facing reset
   (setupPoint pins facing=1).
 - The scratchpad venv/scripts get wiped between sessions — recreate venv (requests+pillow)