feat(sasch40): overhaul Act III tavern schankraum and canonical papa markus scene

- Generate and integrate authentic 16-bit LucasArts taproom scene with Theke, brass taps, bartender, drinking patrons, and bunker trapdoor
- Realign Schankraum hotspots for Verena, Lutz in hot tub, Armend at forge, room transitions, and centered bunker trapdoor
- Update Papa Markus canonical portrait and Taiwan street dining scene to be bald and clean-shaven with glasses and modern attire
- Enforce hotspot zero-occlusion rules for signposts, characters, and mobile room navigation bars
- Document Papa Markus specifications, tavern invariants, and layout guidelines in AGENTS.md
- Add automated sister capture and playthrough recording scripts

projects/sasch40/frontend/src/components/PlatformerView.vue

@@ -166,7 +166,8 @@ function onRight(pressed: boolean) {
 defineExpose({
   onJump,
   onLeft,
-  onRight
+  onRight,
+  triggerSisterRescue
 })
 
 // Touch controls on screen halves
@@ -357,9 +358,11 @@ function drawGame(ctx: CanvasRenderingContext2D) {
 
   // 1. Background sky parallax
   if (bgImg && bgImg.complete && bgImg.naturalWidth > 0) {
-    const scrollFactor = (cameraY / (levelHeight - H))
-    const bgY = -scrollFactor * (bgImg.naturalHeight - H)
-    ctx.drawImage(bgImg, 0, bgY, W, bgImg.naturalHeight * (W / bgImg.naturalWidth))
+    const drawnH = bgImg.naturalHeight * (W / bgImg.naturalWidth)
+    const maxScroll = Math.max(0, drawnH - H)
+    const scrollFactor = Math.max(0, Math.min(1, cameraY / (levelHeight - H)))
+    const bgY = -scrollFactor * maxScroll
+    ctx.drawImage(bgImg, 0, bgY, W, drawnH)
   } else {
     // Fallback sky gradient
     const skyGrad = ctx.createLinearGradient(0, 0, 0, H)
@@ -603,6 +606,11 @@ function gameLoop() {
 onMounted(() => {
   window.addEventListener('keydown', handleKeyDown)
   window.addEventListener('keyup', handleKeyUp)
+  ;(window as any).__platformer = {
+    triggerSisterRescue,
+    setRescuedSister: (s: any) => { rescuedSister.value = s },
+    startLevel
+  }
   initCurrentLevel()
   animationFrameId = requestAnimationFrame(gameLoop)
 })
@@ -610,6 +618,7 @@ onMounted(() => {
 onUnmounted(() => {
   window.removeEventListener('keydown', handleKeyDown)
   window.removeEventListener('keyup', handleKeyUp)
+  delete (window as any).__platformer
   if (animationFrameId) cancelAnimationFrame(animationFrameId)
 })
 </script>