Split notification routes, hard wrap, sort order

Change the notifications subpages to be distinct route handlers with
actual paths rather than query parameters. They already were a massive
conditional chain with almost no common logic.

Hard wrap some of the more egregious query lines. Use less duplicated
code for shadowban exclusion.

Only major functionality change which is somewhat related to #476 is
to sort subtrees by Comment.id DESC. Otherwise, upstream is
substantially the same as TheMotte. Given that upstream didn't
experience #476, I think the issue may have been resolved by prior
changes to filtering / comment visibility & moderation.

files/helpers/services.py

@@ -26,7 +26,7 @@ def pusher_thread2(interests, notifbody, username):
 				'notification': {
 					'title': f'New message from @{username}',
 					'body': notifbody,
-					'deep_link': f'{SITE_FULL}/notifications?messages=true',
+					'deep_link': f'{SITE_FULL}/notifications/messages',
 					'icon': SITE_FULL + assetcache_path(f'images/{SITE_ID}/icon.webp'),
 				}
 			},
@@ -36,7 +36,7 @@ def pusher_thread2(interests, notifbody, username):
 					'body': notifbody,
 				},
 				'data': {
-					'url': '/notifications?messages=true',
+					'url': '/notifications/messages',
 				}
 			}
 		},