feat: add comprehensive Sieve email filtering rules

feat: add rules.sieve

feat: add German translations to email filtering rules

fix: sieve script regex errors

machines/moritz-server/mail-server.nix

@@ -27,6 +27,7 @@
       "main@moritz.place" = {
         hashedPasswordFile = config.clan.core.vars.generators.mail-server.files.main-password-hash.path;
         aliases = ["@moritz.place"];
+        sieveScript = builtins.readFile ./rules.sieve;
       };
     };