feat: converter reads the Phone library's register statement, named stores and generators

`init phone register` becomes a default (the group chat) plus a function of library calls that runs with
the other defaults of a new game (phone_register.py). `init/python [early|hide] in some.store` wraps its
code in an in_store node and `default some.store.name` may name a store; yield works as an expression
(generator functions are marked gen); `import x as y`, `transform -150 name(...)`, `init:` with if/else,
`config.special_namespaces` lines, `at` lists and tuples, transforms made by Python functions, `choice`
weights that are expressions, `__len__`/`__bool__`, and the whitelist for os, calendar, itertools,
pygame_sdl2 and the new runtime. The converter also records the size of every picture it converts
(`imageSizes`) so `renpy.image_size` answers without loading.

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

backend/app/converter/pipeline.py

@@ -134,11 +134,16 @@ def convert_archive(archive: Path, filename: str, work: Path, progress: Progress
     failed: list[str] = []
     done = 0
 
+    image_sizes: dict[str, list[int]] = {}
+
     def work_one(p: Path) -> tuple[str, str, str, int]:
+        dimensions = _dimensions(p)
         out, ext = assets.convert(p, out_dir)
         blob_id, size = put_file(out, ext, move=True)
         rel = p.relative_to(game_dir).as_posix()
         logical = str(PurePosixPath(rel).with_suffix(ext))
+        if dimensions:
+            image_sizes[logical] = dimensions  # the game asks for them (`renpy.image_size`) before anything is loaded
         return rel, logical, blob_id, size
 
     with ThreadPoolExecutor(max_workers=get_settings().worker_threads) as pool:
@@ -223,6 +228,7 @@ def convert_archive(archive: Path, filename: str, work: Path, progress: Progress
         "build": data.build,
         "files": aliases,
         "dataFiles": data_files,
+        "imageSizes": image_sizes,
         "defaults": data.defaults,
         "init": data.init_code,
         "ui": _ui(gui, aliases),
@@ -342,6 +348,19 @@ def _used_screens(data: ScriptData) -> set[str]:
 DATA_FILE_LIMIT = 4 * 1024 * 1024
 
 
+def _dimensions(path: Path) -> list[int] | None:
+    """Width and height of a picture, read from its header (None for other media)."""
+    if assets.kind_of(path) != "image":
+        return None
+    try:
+        from PIL import Image
+
+        with Image.open(path) as img:
+            return [int(img.size[0]), int(img.size[1])]
+    except Exception:  # noqa: BLE001 - the conversion itself reports a broken picture
+        return None
+
+
 def _is_engine_file(game_dir: Path, p: Path) -> bool:
     parts = [x.lower() for x in p.relative_to(game_dir).parts]
     return len(parts) > 1 and parts[0] in ENGINE_DIRS