Implement takedown system

pug/includes/layout.pug

@@ -34,7 +34,7 @@ html
           p Released as AGPL free software.
           .footer__cols
             div
-              h3.footer__colhead Source
+              h3.footer__colhead Source code
               ul.footer__list
                 li: a(href="https://sr.ht/~cadence/tube") Project hub
                 li: a(href="https://lists.sr.ht/~cadence/tube-announce") Announcements
@@ -44,3 +44,5 @@ html
               ul.footer__list
                 li: a(href="/privacy") Privacy policy
                 li: a(href="/licenses" data-jslicense=1) Licenses
+                if constants.takedown
+                  li: a(href="/takedown") DMCA

pug/takedown-video.pug

@@ -0,0 +1,22 @@
+extends includes/layout
+
+include includes/video-list-item
+include includes/subscribe-button
+
+block head
+  title Unavailable for legal reasons - CloudTube
+
+block content
+  main.video-error-page
+    h2 Unavailable for legal reasons
+    p The copyright holders of this video issued a legal notice directly to this website. They demanded that access to this particular video, or the particular channel it's from, should be forbidden.
+    if org
+      p The notice was issued by #{org}.
+    if url
+      p: a(href=url) More information about the notice is available here.
+    p Any content not covered by this notice is still available.
+    p You can still #[a(href=`https://www.youtube.com/watch?v=${id}#cloudtube`) watch the video on YouTube.]
+    footer.takedown-footer
+      p: i Let this be a warning of why you shouldn't rely on centralised services!
+      p: i You will always be able to download the CloudTube source code, or try another instance.
+      p: i That's all we know.

pug/takedown.pug

@@ -0,0 +1,33 @@
+extends includes/layout
+
+block head
+  title Takedown - CloudTube
+
+block content
+  main.takedown-page
+    h1 Takedown/DMCA
+    p If you own the copyright to videos on this website, you can remove access to the videos. But:
+    section.important-section
+      h2 Read this first.
+      ul
+        li CloudTube is a proxy service for YouTube videos.
+        li CloudTube does not store any videos. Videos are never saved to these servers.
+        li CloudTube reproduces data from youtube.com in an interface that looks a little bit different.
+        li All video data is streamed directly from YouTube. All video metadata is collected directly from YouTube.
+      h2 And understand this:
+      p Anybody can watch or download YouTube videos using many freely available tools. This is just one such tool, and attacking this website will solve none of your problems.
+    h2.new-section “I still want to remove access.”
+    p In addition to the legally mandated information, if you wish for future videos uploaded on the same channel(s) to be restricted, please provide the channel URLs, and state: "Future videos uploaded to the same YouTube channels should also be restricted."
+    p When providing URLs, please format them like so:
+    pre.
+      https://youtube.example.com/watch?v=AAAAAAAAAAA
+      https://youtube.example.com/watch?v=BBBBBBBBBBB
+    p i.e., one URL per line, with no other information on those lines.
+    section.takedown-contact
+      if constants.takedown && constants.takedown.contact_url
+        p: a(href=constants.takedown.contact_url) Contact information is here.
+      else if constants.takedown && constants.takedown.contact_email
+        p: a(href=`mailto:${constants.takedown.contact_email}`) Send email to #{constants.takedown.contact_email}
+      else
+        p You will need to contact the website owner via their domain or hosting provider.
+    p Please allow 5 days for a response.