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/pgvn.py

@@ -71,6 +71,8 @@ def expression(value, depth=0):
                 expression(item, depth + 1)
     elif kind == "star":
         ex("v")
+    elif kind == "yield":
+        ex("v", optional=True)
     elif kind == "lambda":
         parameters(value.get("params"), depth + 1)
         ex("body")
@@ -127,12 +129,16 @@ def statements(code, depth=0):
         keys = {"set": ("t", "v"), "aug": ("t", "v"), "eval": ("e",),
                 "if": ("c",), "while": ("c",), "for": ("t", "it"),
                 "del": ("t",), "break": (), "continue": (), "def": (), "class": (),
-                "return": (), "global": (), "nonlocal": (), "try": (), "raise": (), "yield": (), "yield_from": ("v",),
+                "return": (), "global": (), "nonlocal": (), "try": (), "raise": (), "yield": (), "yield_from": ("v",), "in_store": (),
                 "assert": ("c",)}
         if op not in keys:
             raise ValueError(f"Неизвестный оператор AST: {op}")
         for key in keys[op]:
             expression(s.get(key), depth + 1)
+        if op == "in_store":
+            if not isinstance(s.get("ns"), str) or not all(part.isidentifier() for part in s["ns"].split(".")):
+                raise ValueError("Некорректное имя хранилища")
+            statements(s.get("body"), depth + 1)
         if op == "if":
             statements(s.get("then"), depth + 1)
             statements(s.get("else"), depth + 1)