Add DMS configuration and helper scripts

- Introduced a new `justfile` for managing DMS-related tasks, including a recipe for syncing live DMS configuration.
- Added a `devshell.nix` file to set up a development environment with necessary packages and shell hooks for DMS.
- Updated DMS settings to replace `defaultSettingsFile` with `defaultSeedDir` for improved configuration management.
- Created a new script `sync-seed.sh` to facilitate syncing DMS settings from the live configuration to host-specific directories.
- Enhanced documentation and examples for DMS configuration and usage.

modules/desktop/shells/dms/_private/default-settings.nix

@@ -1,6 +1,8 @@
 # Generic defaults written once to ~/.config/DankMaterialShell/settings.json on first login.
-# Hosts can override via `chiasson.desktop.shells.dms.defaultSettingsFile` (see 14900k).
+# Hosts can override via `chiasson.desktop.shells.dms.defaultSeedDir` (see 14900k).
 # After seeding, DMS settings are owned by the UI — rebuilds do not overwrite them.
+#
+# To refresh host seeds from live DMS config: `just sync-dms`
 {
   lib,
   gpuTempEnabled ? true,

modules/desktop/shells/dms/_private/sync-seed.sh

@@ -0,0 +1,119 @@
+#!/usr/bin/env bash
+# Sync live DMS config into modules/hosts/<host>/_private/dms-defaults/ (see defaultSeedDir).
+set -euo pipefail
+
+usage() {
+  cat <<EOF
+Usage: $(basename "$0") [options] [host]
+
+Copy ~/.config/DankMaterialShell/{settings,plugin_settings}.json into the
+host seed directory (pretty-printed). Host defaults to this machine's hostname.
+
+Options:
+  --settings-only   Skip plugin_settings.json
+  -n, --dry-run     Preview without writing
+  -h, --help
+
+Examples:
+  just sync-dms
+  $(basename "$0") --dry-run ideapad
+EOF
+}
+
+find_repo_root() {
+  local dir="${1:-$PWD}"
+  while [[ "$dir" != "/" ]]; do
+    if [[ -f "$dir/flake.nix" && -d "$dir/modules/hosts" ]]; then
+      printf '%s\n' "$dir"
+      return 0
+    fi
+    dir="$(dirname "$dir")"
+  done
+  return 1
+}
+
+resolve_host_module() {
+  local hn="$1" repo_root="$2"
+  local hosts_dir="${repo_root}/modules/hosts" dir name
+
+  if [[ -d "${hosts_dir}/${hn}/_private" ]]; then
+    printf '%s' "$hn"
+    return 0
+  fi
+
+  for dir in "${hosts_dir}"/*/; do
+    name="$(basename "$dir")"
+    [[ -f "${dir}configuration.nix" ]] \
+      && grep -qF "hostName = \"${hn}\";" "${dir}configuration.nix" \
+      && { printf '%s' "$name"; return 0; }
+  done
+
+  echo "error: no host module for hostname '${hn}' (pass module name explicitly)" >&2
+  return 1
+}
+
+sync_json() {
+  local source="$1" dest="$2" label="$3"
+
+  [[ -f "$source" ]] || { echo "skip: $label not found" >&2; return 0; }
+
+  jq empty "$source"
+  if [[ "$DRY_RUN" -eq 1 ]]; then
+    echo "  $source -> $dest"
+    return 0
+  fi
+
+  local tmp
+  tmp="$(mktemp)"
+  jq . "$source" >"$tmp"
+  mv "$tmp" "$dest"
+  echo "Updated $dest"
+  UPDATED+=("$dest")
+}
+
+DRY_RUN=0
+SETTINGS_ONLY=0
+HOST=""
+UPDATED=()
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    -n | --dry-run) DRY_RUN=1; shift ;;
+    --settings-only) SETTINGS_ONLY=1; shift ;;
+    -h | --help) usage; exit 0 ;;
+    -*) echo "error: unknown option: $1" >&2; usage >&2; exit 1 ;;
+    *) HOST="$1"; shift ;;
+  esac
+done
+
+REPO_ROOT="${CHIASSON_NIX_ROOT:-$(find_repo_root "$PWD" || true)}"
+[[ -n "$REPO_ROOT" ]] || { echo "error: run from chiasson-nix repo root" >&2; exit 1; }
+command -v jq >/dev/null || { echo "error: jq required" >&2; exit 1; }
+
+if [[ -z "$HOST" ]]; then
+  SYSTEM_HOSTNAME="$(hostname -s 2>/dev/null || hostname)"
+  HOST="$(resolve_host_module "$SYSTEM_HOSTNAME" "$REPO_ROOT")"
+  [[ "$HOST" == "$SYSTEM_HOSTNAME" ]] \
+    && echo "Using host module: $HOST" \
+    || echo "Using host module: $HOST (hostname: $SYSTEM_HOSTNAME)"
+fi
+
+HOST_PRIVATE="${REPO_ROOT}/modules/hosts/${HOST}/_private"
+SEED_DIR="${HOST_PRIVATE}/dms-defaults"
+DMS_CONFIG="${XDG_CONFIG_HOME:-$HOME/.config}/DankMaterialShell"
+
+[[ -d "$HOST_PRIVATE" ]] || { echo "error: missing $HOST_PRIVATE" >&2; exit 1; }
+[[ -f "${DMS_CONFIG}/settings.json" ]] || {
+  echo "error: missing ${DMS_CONFIG}/settings.json" >&2
+  exit 1
+}
+
+[[ "$DRY_RUN" -eq 1 ]] && echo "Would sync into $SEED_DIR:"
+[[ "$DRY_RUN" -eq 0 ]] && mkdir -p "$SEED_DIR"
+
+sync_json "${DMS_CONFIG}/settings.json" "${SEED_DIR}/settings.json" settings.json
+[[ "$SETTINGS_ONLY" -eq 0 ]] \
+  && sync_json "${DMS_CONFIG}/plugin_settings.json" "${SEED_DIR}/plugin_settings.json" plugin_settings.json
+
+[[ "$DRY_RUN" -eq 1 || ${#UPDATED[@]} -eq 0 ]] && exit 0
+git -C "$REPO_ROOT" diff --stat -- "${UPDATED[@]}" 2>/dev/null || true