feat: drag boxes, transforms as values, Matrix() colours and offline renpy.fetch in the player

screens: `drag` with draggable True moves with the pointer (the place is kept while the screen is
shown); `at icon["at"]` picks a transform that Python code stored in a dict (transform names now
evaluate to a reference); PreviewSlowText and Move(...) exist as values. Python: Matrix([16 numbers])
for matrixcolor, renpy.has_live2d() is false, renpy.fetch fails like a missing network (games catch
it), cache.get_total_size and the texture helpers are no-ops.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

frontend/src/player/screens.ts

@@ -66,6 +66,11 @@ type Props = Record<string, any>;
 
 class ActionAbort extends Error {}
 
+/** A transform used as a value: `{"at": move_in}`; `at icon["at"]` then applies it. */
+export class TransformRef {
+  constructor(public name: string) {}
+}
+
 /** A screen action such as Jump("x"); run when the player activates a widget. */
 export class ScreenAction {
   /** Actions are callable in Ren'Py: `MainMenu(confirm=False)()` performs the action at once. */
@@ -571,6 +576,7 @@ export class ScreenManager {
   private widget(node: any, ctx: Ctx): HTMLElement | null {
     switch (node.w) {
       case "fixed": return this.container(node, ctx, "div", "abs", ["fixed"], true);
+      case "drag": return this.dragBox(node, ctx);
       case "frame":
       case "window": return this.container(node, ctx, "div", "stack", [node.w, "frame"]);
       case "vbox": return this.container(node, ctx, "div", "col", ["vbox"]);
@@ -594,6 +600,31 @@ export class ScreenManager {
     return null;
   }
 
+  /** A box the player can move with the pointer; where it was left is kept while the screen is shown. */
+  private dragBox(node: any, ctx: Ctx): HTMLElement {
+    const el = this.container(node, ctx, "div", "abs", ["fixed"]);
+    const props = this.resolve(node, ctx, ["fixed"]);
+    if (!truthy(this.pick(props, "draggable"))) return el;
+    const key = `__drag:${pyStr(this.pick(props, "drag_name") ?? "")}`;
+    const place = (ctx.inst.vars.get(key) ?? [0, 0]) as [number, number];
+    el.style.translate = `${place[0]}px ${place[1]}px`;
+    el.style.cursor = "grab";
+    el.onpointerdown = (down) => {
+      if ((down.target as HTMLElement).closest("button, [role=button], .pg-sbutton")) return;
+      down.stopPropagation();
+      el.setPointerCapture(down.pointerId);
+      const start = [...place] as [number, number];
+      el.onpointermove = (move) => {
+        place[0] = start[0] + (move.clientX - down.clientX);
+        place[1] = start[1] + (move.clientY - down.clientY);
+        el.style.translate = `${place[0]}px ${place[1]}px`;
+        ctx.inst.vars.set(key, [...place]);
+      };
+      el.onpointerup = () => { el.onpointermove = null; el.onpointerup = null; };
+    };
+    return el;
+  }
+
   private container(node: any, ctx: Ctx, tag: string, layout: Ctx["layout"], kinds: string[], fill = false): HTMLElement {
     const el = document.createElement(tag);
     const props = this.resolve(node, ctx, kinds);
@@ -1345,7 +1376,12 @@ export class ScreenManager {
 
   /** `at` transforms: static properties now, animated ones through the ATL runner. */
   private transforms(el: HTMLElement, props: Record<string, Expr>, ctx: Ctx) {
-    const pick = (spec: AtSpec): AtSpec => (spec.choose ? pick(truthy(this.ev(spec.choose.c)) ? spec.choose.then : spec.choose.else) : spec);
+    const named = (value: any): AtSpec => {
+      const name = value instanceof TransformRef ? value.name : typeof value === "string" ? value : "";
+      return name ? { name, atl: this.host.atl(name) ? name : undefined } : {};
+    };
+    const pick = (spec: AtSpec): AtSpec => (spec.choose ? pick(truthy(this.ev(spec.choose.c)) ? spec.choose.then : spec.choose.else)
+      : spec.dyn ? named(this.ev(spec.dyn)) : spec);
     const specs: AtSpec[] = Array.isArray((props as any).at) ? (props as any).at.map(pick) : [];
     const live: Props = {};
     const apply = (p: Props) => {
@@ -1714,6 +1750,9 @@ export class ScreenManager {
     out.Flatten = (child: any) => child; // flattening only changes how the browser composites, not what is drawn
     out.AlphaMask = shape("alphamask");
     out.TrackCursor = shape("trackcursor");
+    out.PreviewSlowText = shape("text");
+    out.Move = (...a: any[]) => ({ __transition: "move", args: a }); // `default vpunch = Move(...)`: the effect itself is chosen by `with`
+    out.absolute = (x: any) => Number(x);
     out.At = (child: any) => child;
     Object.assign(out, colorMatrices);
     out.im = {