feat: File* save/load actions, hashlib/uuid, dict spread and small renpy helpers in the player

Games with their own save screens work: FileAction/FileSave/FileLoad/FileDelete/FilePage*, FileLoadable,
FileTime, FileSaveName, FileJson and friends use browser slots (a slot has no screenshot). Added
renpy.has_image/has_screen/list_files/get_mouse_pos/log/jump_out_of_context/random.seed,
renpy.translation.translate_string, type/id/vars/Flatten/LiveComposite/Composite, bare defaultdict/
deepcopy, md5/sha256 (checked against test vectors), uuid4, time.monotonic, re.compile().fullmatch,
math.isfinite and `{**a, "k": v}`. The converter whitelists them and accepts the hashlib/uuid imports.

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

backend/app/converter/pyexpr.py

@@ -25,7 +25,7 @@ UNARY_OPS = {ast.Not: "not", ast.USub: "-", ast.UAdd: "+", ast.Invert: "~"}
 
 # Modules whose import is harmless: the player provides the functions it supports.
 KNOWN_MODULES = {"random", "math", "renpy", "store", "time", "datetime", "re", "copy", "collections",
-                 "itertools", "string", "functools", "operator", "json", "gc"}
+                 "itertools", "string", "functools", "operator", "json", "gc", "hashlib", "uuid"}
 
 
 class Unsupported(Exception):
@@ -146,9 +146,9 @@ def expr(node: ast.AST) -> Expr:
         case ast.Tuple(elts=elts):
             return {"k": "tuple", "v": [expr(e) for e in elts]}
         case ast.Dict(keys=keys, values=values):
-            if any(k is None for k in keys):
-                raise Unsupported("распаковка ** в словаре")
-            return {"k": "dict", "v": [[expr(k), expr(v)] for k, v in zip(keys, values)]}
+            # `{**other, "k": v}`: a spread entry is a star key with an empty value
+            return {"k": "dict", "v": [[{"k": "star", "v": expr(v)}, {"k": "const", "v": None}] if k is None
+                                       else [expr(k), expr(v)] for k, v in zip(keys, values)]}
         case ast.Call(func=func, args=args, keywords=kws):
             call = {"k": "call", "f": expr(func),
                     "a": [{"k": "star", "v": expr(a.value)} if isinstance(a, ast.Starred) else expr(a)