fix(iso): zoom direction + wall cutaway for readable openings

Zoom: the wheel handler based its step on a hardcoded 1.7, but iso defaults to 1.0 — so the first
scroll (either direction) jumped up to ~1.7 and read as "always zoom in". Base the step on the
CURRENT effective zoom via SP._defaultZoom() instead. Same mode-aware default now used by the camera.

Iso occlusion: tall walls (184px) hide the floor/openings behind them (inherent to iso painter
order). Add a cutaway — walls between the camera and the player (higher x+y, within ~3 cells) draw
at 0.28 alpha so you can see yourself and the openings right in front of you.

html/js/render/isoRenderer.js

@@ -313,7 +313,7 @@
             p = this._project(e.x, e.y, originX, originY);
             items.push({ type: 'entity', e: e, sx: p.x, sy: p.y, depth: e.x + e.y + 0.55 });
             // Sticky camera target (keep last if the player is momentarily absent).
-            if (e.you || e.kind === 'player') this.focusPoint = { x: p.x, y: p.y + this.tileH };
+            if (e.you || e.kind === 'player') { this.focusPoint = { x: p.x, y: p.y + this.tileH }; this._plx = e.x; this._ply = e.y; }
         }
         items.sort(function (a, b) { return a.depth === b.depth ? (a.y || 0) - (b.y || 0) : a.depth - b.depth; });
 
@@ -325,8 +325,17 @@
                 if (WALLISH[tileKind]) tileKind = this._wallVariant(scene, it.x, it.y, tileKind);
                 else tileKind = this._floorVariant(tileKind, it.x, it.y);
                 var rec = this._load(this._tileUrl(tileKind));
+                // Cutaway: fade the walls sitting between the camera and the player (higher x+y, toward
+                // the SE camera, within a few cells) so they don't hide the player or the openings right
+                // in front of them. Iso occlusion otherwise makes near hallways impossible to read.
+                var cut = WALLISH[it.kind] && this._plx != null &&
+                    it.x >= this._plx && it.y >= this._ply &&
+                    (it.x + it.y) > (this._plx + this._ply) &&
+                    ((it.x - this._plx) + (it.y - this._ply)) <= 3;
+                if (cut) ctx.globalAlpha = 0.28;
                 if (rec && rec.ready) this._drawImage(rec.img, it.sx, it.sy + this.tileH, this.imageW, this.imageH);
                 else if (it.kind !== 'dark') this._diamond(it.sx, it.sy + this.tileH * 0.5, (legend[it.kind] && legend[it.kind].color) || '#3a4048');
+                ctx.globalAlpha = 1;
             } else if (it.type === 'prop') {
                 this._contactShadow(it.sx, it.sy + this.tileH * 1.4, 22, 9);
                 rec = this._load(this._tileUrl(it.kind));

html/js/render/spGameRenderer.js

@@ -112,13 +112,23 @@
             host._rkZoomBound = true;
             host.addEventListener('wheel', function (ev) {
                 ev.preventDefault();
-                SP._zoom = Math.max(0.6, Math.min(4, (SP._zoom || 1.7) * Math.exp(-ev.deltaY * 0.0015)));
+                // Base the step on the CURRENT effective zoom (mode-aware default if not yet set),
+                // NOT a hardcoded 1.7 — otherwise the first scroll on iso (default 1.0) jumped up to
+                // 1.7 and BOTH directions read as "zoom in".
+                var base = (SP._zoom != null) ? SP._zoom : SP._defaultZoom();
+                SP._zoom = Math.max(0.4, Math.min(4, base * Math.exp(-ev.deltaY * 0.0015)));
                 SP._applyCamera();
             }, { passive: false });
         }
         return SP._renderer;
     };
 
+    // Mode-aware default zoom: iso tiles are large (84px) so they want less magnification than the
+    // small tiled/ascii cells (~24px).
+    SP._defaultZoom = function () {
+        return (SP._renderer && SP._renderer.name === 'iso') ? 1.0 : 1.7;
+    };
+
     // Centre the (whole-scene) canvas on the player via a CSS transform, clipped to the host —
     // renderer-agnostic (works for tiled / iso / 3d, each of which reports its own focusPoint).
     SP._applyCamera = function () {
@@ -133,9 +143,7 @@
             r.canvas.style.top = '0';
             return;
         }
-        // Default zoom is mode-aware: iso tiles are large (84px), so a lower default frames a sensible
-        // number of them; tiled/ascii cells are small (~24px) so they want more magnification.
-        var scale = SP._zoom || (r.name === 'iso' ? 1.0 : 1.7);
+        var scale = (SP._zoom != null) ? SP._zoom : SP._defaultZoom();
         var fp = r.focusPoint;
         // ROBUSTNESS: if the renderer hasn't reported a focus this frame — a race at game start, or a
         // camera tick reading a just-(re)created renderer instance before its first render — derive the