feat: add videodb media index with Docker stack

- Add videodb PHP/MySQL media collection manager (Blu-ray, DVD, CD)
- Dockerfile: PHP 8.1 + Apache with GD/mysqli/exif extensions
- docker-compose.yml: app on port 6761 + MySQL 8.0 with health checks
- docker-entrypoint.sh: auto-generates config.inc.php from env vars,
  waits for MySQL, initializes DB schema idempotently
- init-db.php: CLI schema installer using app's own prefix_query() logic
- Persistent volumes for DB, cache, and cover images

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

videodb/contrib/setGenre.pl

@@ -0,0 +1,54 @@
+#!/usr/bin/perl
+
+# Set title
+$TITLE="South Park";
+
+# Set genres (see list below for ids)
+@GENRES=(4,3);
+
+#  1  Action
+#  2  Adventure
+#  3  Animation
+#  4  Comedy
+#  5  Crime
+#  6  Documentary
+#  7  Drama
+#  8  Family
+#  9  Fantasy
+# 10  Film-Noir
+# 11  Horror
+# 12  Musical
+# 13  Mystery
+# 14  Romance
+# 15  Sci-Fi
+# 16  Short
+# 17  Thriller
+# 18  War
+# 19  Western
+
+$db_server    = "localhost";
+$db_user      = "www";
+$db_password  = "leech";
+$db_database  = "VideoDB";
+
+######################################################################
+use DBI;
+$dbh = DBI->connect("dbi:mysql:$db_database:$db_server",$db_user,$db_password) || die("Can't connect");
+
+$SELECT = "SELECT id from videodata
+            WHERE title LIKE '$TITLE'";
+$idr = $dbh->selectall_arrayref($SELECT);
+
+$row=0;
+while (defined($idr->[$row][0])){
+  my $id = $idr->[$row][0];
+
+  #clear existing genres:
+  $dbh->do("DELETE FROM videogenre WHERE id = $id");
+
+  #insert new genres
+  foreach my $gid (@GENRES){  
+    $dbh->do("INSERT INTO videogenre SET id = $id, gid = $gid");
+  }
+  $row++;
+}