feat: port Hatena server to Python 3

* Update server-side database and dynamic resource code for Python 3
* Preserve existing Flipnote, UGO, NTFT, CSS, localization, and Hatena assets
* Port Flipnote upload and movie endpoints
* Update front page UGO menu generators
* Preserve existing database and sample Flipnote data
* Add regression tests for database operations and binary formats
* Add server resource loading tests
* Maintain compatibility with the original DSi Flipnote Studio protocol

tests/test_server_resources.py

@@ -0,0 +1,124 @@
+from __future__ import annotations
+
+import importlib
+import sys
+import types
+import unittest
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def install_twisted_stub():
+    """Install only the Twisted surface needed to smoke-test this project."""
+    if importlib.util.find_spec("twisted") is not None:
+        return
+
+    twisted = types.ModuleType("twisted")
+    web = types.ModuleType("twisted.web")
+    resource_mod = types.ModuleType("twisted.web.resource")
+    static_mod = types.ModuleType("twisted.web.static")
+    internet_mod = types.ModuleType("twisted.internet")
+
+    class Resource:
+        isLeaf = False
+
+        def __init__(self):
+            self.children = {}
+
+        def putChild(self, name, child):
+            if not isinstance(name, bytes):
+                raise TypeError("Twisted child names must be bytes")
+            self.children[name] = child
+
+        def getChild(self, name, request):
+            return self
+
+        def getChildWithDefault(self, name, request):
+            return self.children.get(name, self.getChild(name, request))
+
+    class File(Resource):
+        def __init__(self, path):
+            super().__init__()
+            self.path = path
+
+        def render(self, request):
+            p = Path(self.path)
+            return p.read_bytes() if p.is_file() else b""
+
+    class Reactor:
+        def __init__(self):
+            self.calls = []
+
+        def callLater(self, delay, func, *args, **kwargs):
+            self.calls.append((delay, func, args, kwargs))
+            return object()
+
+        def callInThread(self, func, *args, **kwargs):
+            return func(*args, **kwargs)
+
+    resource_mod.Resource = Resource
+    static_mod.File = File
+    web.resource = resource_mod
+    web.static = static_mod
+    internet_mod.reactor = Reactor()
+    twisted.web = web
+    twisted.internet = internet_mod
+
+    sys.modules.update(
+        {
+            "twisted": twisted,
+            "twisted.web": web,
+            "twisted.web.resource": resource_mod,
+            "twisted.web.static": static_mod,
+            "twisted.internet": internet_mod,
+        }
+    )
+
+
+class ResourceTreeTests(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        install_twisted_stub()
+        cls.old_cwd = Path.cwd()
+        import os
+        os.chdir(ROOT)
+        import hatena
+        cls.hatena = hatena
+        cls.root = hatena.Setup()
+
+    @classmethod
+    def tearDownClass(cls):
+        import os
+        os.chdir(cls.old_cwd)
+
+    def test_core_resource_tree_loads(self):
+        region = self.root.dsResource.region
+        expected = {
+            b"index.ugo",
+            b"inbox.ugo",
+            b"movie",
+            b"post",
+            b"frontpage",
+            b"help",
+            b"eula_list.tsv",
+        }
+        self.assertTrue(expected.issubset(region.children))
+        self.assertIn(b"flipnote.post", region.children[b"post"].children)
+        self.assertIn(b"hotmovies.ugo", region.children[b"frontpage"].children)
+        self.assertIn(b"likedmovies.ugo", region.children[b"frontpage"].children)
+        self.assertIn(b"newmovies.ugo", region.children[b"frontpage"].children)
+
+    def test_prepacked_ugo_resources_are_binary(self):
+        region = self.root.dsResource.region
+        self.assertTrue(region.children[b"index.ugo"].ugofile.startswith(b"UGAR"))
+        self.assertTrue(region.children[b"inbox.ugo"].ugofile.startswith(b"UGAR"))
+
+    def test_hot_page_builds_from_database(self):
+        hot = self.root.dsResource.region.children[b"frontpage"].children[b"hotmovies.ugo"]
+        self.assertGreaterEqual(len(hot.pages), 1)
+        self.assertTrue(hot.pages[0].startswith(b"UGAR"))
+
+
+if __name__ == "__main__":
+    unittest.main()