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

hatenadir/images/ds/thumb_down.ntft

@@ -0,0 +1 @@
+���™�5�5�5�5�5�5�5�5�������™��γ?Οό�ό�?Ο?Ο?Ο?Ο?Ο5�5�����™��γ?Ο?Ο?Οό�?Ο�γ�γ?Ο?Ο?Ο5����ό�ό�ό�ό�ό�?Ο?Ο�γ�γ�γ�γ�γ?Ο5���™��γ?Ο?Ο?Οό�?Ο?Ο?Ο?Ο?Ο�γ�γ5���ό�ό�ό�ό�ό�?Ο?Οό�ό�ό�?Ο�γ�γ™���™��γ?Ο?Ο?Οό�ό�?Ο?Ο?Ο?Ο�γ�γ™���ό�ό�ό�ό�ό�?Ο?Ο?Ο�γ�γ�γ?Ο?Ο5���™��γ�γ�γ�γό�?Ο�γ�γ�γ?Ο?Ο5�����™�™�™�™�5�?Ο?Ο?Ο?Ο5�5����������5�?Ο?Ο?Ο5�����������™�?Ο?Ο?Ο5�����������™��γ?Ο?Ο5������������™��γ?Ο?Ο5������������™��γ�γ�γ™�������������™�™�™��������