feat: ATL pictures/contains/function/time, colour matrices and more Python for Ren'Py

ATL
- Image blocks become timelines: picture steps with dissolve, parallel, contains,
  finite repeat, time, function f(trans, st, at), calls of other transforms with
  arguments, on hover/idle events for buttons. Animations stop when their element
  leaves the page
- Pictures defined by an expression (get_face_path("base")) are drawn at show time
- Purely graphical hints (shader, mesh, gl_*, u_*) are accepted and dropped

Colour
- matrixcolor and im.matrix.* as 5x5 matrices combined with `*`, applied through SVG
  filters; im.MatrixColor/Scale/Crop/Blur/Composite and Text/Image as values

Python
- match statement, re/copy/time/datetime/defaultdict/functools.partial, more
  str/dict methods, Character(...) created by code
- narrator("..."), Character calls, renpy.say and renpy.show/hide with expressions in
  Python blocks become script nodes
- Audit follows reachability: functions and classes nothing refers to (custom
  statement lexers, unused tools) no longer block an import

Docs: README and ARCHITECTURE now describe a multi-engine library (GameMaker and
QSP planned). Tests for the new runtime pieces.

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

frontend/src/player/engine.ts

@@ -7,6 +7,7 @@ import { fastPoint, interpolate, parseText, plainText, renderText, waitPoints }
 import { languageName, rememberLanguage, type Translator } from "./i18n";
 import { naniText } from "./naninovel";
 import { ScreenManager, type ScreenHost } from "./screens";
+import { pythonModules } from "./pymodules";
 import { DEFAULT_SETTINGS, SLOTS, Restart, el, loadJSON, saveJSON, type SaveApi, type SaveMeta, type Settings } from "./engine-util";
 import type {
   CharacterDef, Expr, Frame, GameData, ImageDef, Label, Layer, Manifest, Node, SaveData, ScriptModule,
@@ -321,6 +322,20 @@ export class Engine {
       ...this.screens.renpyApi(),
       // presentation-only: nothing to roll back or replay, and the next transition is chosen by `with`
       end_replay: () => null,
+      partial: (f: any, ...bound: any[]) => (...args: any[]) => f(...bound, ...args),
+      loadable: (path: any) => this.fileUrl(String(path)) !== null,
+      is_init_phase: () => false,
+      call_stack_depth: () => this.stack.length,
+      const: (value: any) => value,
+      screenshot: () => null,
+      Keymap: () => null,
+      register_shader: () => null,
+      register_statement: () => null,
+      redraw: () => null,
+      stop_predict: () => null,
+      map_event: () => null,
+      count_displayables_in_layer: () => 0,
+      displayable: (value: any) => value,
       variant: (name: string) => ["pc", "large", "web", "medium"].includes(String(name)),
       change_language: (code: any) => void this.setLanguage(code === null || code === undefined ? this.game.sourceLang ?? "und" : String(code)),
       seen_image: (name: any) => this.seenImages.has(String(name)),
@@ -351,6 +366,10 @@ export class Engine {
       len: (x: any) => (x instanceof PyDict ? x.map.size : x?.length ?? 0),
       // a read-only view: `"name" in globals()` works, writes do not reach the game
       globals: () => new PyDict(Object.entries(this.store)),
+      print: () => null,
+      ...pythonModules(),
+      _window_hide: () => { this.windowShown = false; this.textbox.classList.add("pg-hidden"); return null; },
+      _window_show: () => { this.windowShown = true; return null; },
       ...Object.fromEntries(["Dissolve", "Fade", "ImageDissolve", "MoveTransition", "CropMove", "PushMove",
         "Pixellate", "ComposeTransition", "With"].map((n) => [n, () => null])),
       str: (x: any) => pyStr(x),
@@ -429,6 +448,8 @@ export class Engine {
         if (/^https?:\/\//i.test(url)) window.open(url, "_blank", "noopener,noreferrer");
       },
       setLanguage: (code) => void this.setLanguage(code ?? this.game.sourceLang ?? "und"),
+      quickSave: () => void this.save("quick"),
+      quickLoad: () => void this.load("quick"),
       transform: (name) => this.game.transforms[name] ?? null,
       atl: (name) => this.game.atl?.[name] ?? null,
     };
@@ -729,7 +750,7 @@ export class Engine {
           this.renderer.scene();
           this.clearNvl();
         }
-        if (node.op === "hide") this.renderer.hide(node.tag);
+        if (node.op === "hide") this.renderer.hide(node.tagExpr ? pyStr(this.safeEval(node.tagExpr)).split(" ")[0] : node.tag);
         else if (node.img) this.showNode(node);
         if (node.with) await this.renderer.transition(this.transition(node.with));
         this.advance();
@@ -878,7 +899,11 @@ export class Engine {
   }
 
   private characterFor(node: Node): { char: CharacterDef; name: string; mode: string } {
-    const who: string | undefined = node.who;
+    let who: string | undefined = node.who;
+    if (node.whoExpr) {
+      const value = this.safeEval(node.whoExpr);
+      who = typeof value === "string" ? value : undefined;
+    }
     if (this.game.engine === "naninovel" && node.whoStr !== undefined) {
       const entry = this.game.naniResources?.CharacterNames?.[node.whoStr]?.[0];
       return { char: {}, name: this.interp(entry ? this.tr.line(entry.tid, entry.text) : this.tr.str(node.whoStr)), mode: "adv" };
@@ -891,6 +916,9 @@ export class Engine {
     const char = this.game.characters[who];
     if (!char) {
       const v = this.store[who];
+      if (v && typeof v === "object" && v.__character) {
+        return { char: { color: v.color ?? undefined }, name: this.interp(this.tr.str(v.name ?? who)), mode: "adv" };
+      }
       return { char: {}, name: typeof v === "string" ? v : who, mode: "adv" };
     }
     let name = this.tr.str(char.name ?? "");
@@ -927,7 +955,9 @@ export class Engine {
     if (!inMenu) this.interactionStart();
     if (node.with) await this.renderer.transition(this.transition(node.with));
 
-    let raw = this.interp(this.tr.line(node.tid, node.what));
+    let raw = node.whatExpr
+      ? this.interp(pyStr(this.safeEval(node.whatExpr)))
+      : this.interp(this.tr.line(node.tid, node.what));
     raw = `${char.whatPrefix ?? ""}${raw}${char.whatSuffix ?? ""}`;
     let prefixLen = 0;
     if (mode === "extend" && this.lastSay) {