fix broken references to deleted files, remove dead code

Build-breaking fixes:
- kibbeh: remove imports of deleted admin-essentials, nix, zsh configs
  (all provided by niphas via profiles.default + profiles.desktop)
- tabula, tahina: remove imports of deleted admin-essentials, nix configs
  (provided by niphas via profiles.default)
- zaatar: remove import of deleted tmux config
  (provided by niphas via profiles.default)

Dead code removal:
- flake.nix: remove nixosModules.zsh-kmein (referenced deleted config/zsh.nix)
- flake.nix: remove unused wallpapers input
- packages/gpt.nix, hora.nix, k-lock.nix: orphaned, not in overlay or referenced
- configs/hledger.nix: remove hora reference (package deleted)

packages/gpt.nix

@@ -1,15 +0,0 @@
-{
-  curl,
-  writers,
-  jq,
-  apiKeyCommand ? "pass api-keys/openai.com",
-  model ? "gpt-3.5-turbo",
-}:
-writers.writeDashBin "gpt" ''
-  json=$(jq --slurp --raw-input '{model:"${model}", messages: [{role: "user", content: .}]}')
-  ${curl}/bin/curl -sSL https://api.openai.com/v1/chat/completions \
-    -H "Content-Type: application/json" \
-    -H "Authorization: Bearer $(${apiKeyCommand})" \
-    -d "$json" \
-    | ${jq}/bin/jq -r '.choices[] | .message.content'
-''

packages/hora.nix

@@ -1,81 +0,0 @@
-{
-  symlinkJoin,
-  hledger,
-  writers,
-  lib,
-  git,
-  coreutils,
-  gnugrep,
-  timeLedger,
-  ...
-}:
-let
-  date = "${coreutils}/bin/date +'%Y-%m-%d %H:%M:%S'";
-
-  hora = writers.writeDashBin "hora" "${hledger}/bin/hledger -f ${lib.escapeShellArg timeLedger} \"$@\"";
-  hora-edit = writers.writeDashBin "hora-edit" "$EDITOR ${lib.escapeShellArg timeLedger}";
-  hora-status = writers.writeDashBin "hora-status" "${coreutils}/bin/tac ${lib.escapeShellArg timeLedger} | ${gnugrep}/bin/grep -m 1 .";
-
-  hora-start = writers.writeDashBin "hora-start" ''
-    last_nonempty_line=$(${hora-status}/bin/hora-status)
-    (echo $last_nonempty_line | ${gnugrep}/bin/grep -q "^o") || {
-        echo "Last activity must be closed: $last_nonempty_line" >/dev/stderr
-        exit 1
-    }
-
-    account=$1
-    (${hora}/bin/hora accounts | ${gnugrep}/bin/grep -q "^$account\$") || {
-        echo "The account '$account' is not known. Please add manually."
-        exit 1
-    }
-
-    message=$2
-    date=$(${date})
-    echo "i $date $account  $message\n" >> "${timeLedger}"
-    echo "Started $account at $date" >/dev/stderr 
-  '';
-
-  hora-stop = writers.writeDashBin "hora-stop" ''
-    last_nonempty_line=$(${hora-status}/bin/hora-status)
-
-    (echo $last_nonempty_line | ${gnugrep}/bin/grep "^i") || {
-        echo "Last activity cannot be closed: $last_nonempty_line" >/dev/stderr
-        exit 1
-    }
-
-    last_activity=$(echo "$last_nonempty_line" | ${coreutils}/bin/cut -d' ' -f 4)
-    date=$(${date})
-
-    echo "o $date\n" >> ${timeLedger}
-    echo "Stopped $last_activity at $date" >/dev/stderr
-  '';
-
-  hora-year = writers.writeDashBin "hora-year" ''
-    ${hora}/bin/hora balance --tree --monthly --begin $(${coreutils}/bin/date +%Y) --depth 1
-  '';
-  hora-git = writers.writeDashBin "hora-git" ''
-    directory=$(${coreutils}/bin/dirname ${lib.escapeShellArg timeLedger})
-    if [ $# -gt 0 ]
-    then
-      ${git}/bin/git -C "$directory" --all --message=$(${date})
-    else
-      ${git}/bin/git -C "$directory" "$@"
-    fi
-  '';
-  hora-weekly = writers.writeDashBin "hora-weekly" ''
-    ${hora}/bin/hora register -p weekly --depth 1 --empty
-  '';
-in
-symlinkJoin {
-  name = "hora";
-  paths = [
-    hora
-    hora-edit
-    hora-start
-    hora-status
-    hora-stop
-    hora-year
-    hora-git
-    hora-weekly
-  ];
-}

packages/k-lock.nix

@@ -1,30 +0,0 @@
-{
-  writers,
-  lib,
-  xlockmore,
-}:
-let
-  xlockModes = lib.concatStringsSep "\\n" [
-    # "braid"
-    "galaxy"
-    # "lightning"
-    # "matrix"
-    "pyro2"
-    "space"
-  ];
-in
-writers.writeDashBin "k-lock" ''
-  MODE=$(printf "${xlockModes}" | shuf -n 1)
-
-  ${xlockmore}/bin/xlock \
-    -saturation 0.4 \
-    -erasemode no_fade \
-    +description \
-    -showdate \
-    -username " " \
-    -password " " \
-    -info " " \
-    -validate "..." \
-    -invalid "Computer says no." \
-    -mode "$MODE"
-''