refactor(#107): theme-state.json → state.json, theme-sync → state-sync

The machine flake's git-tracked settings file is system state, not
"theme" only — rename it to state.json. CLI becomes nomarchy-state-sync
with a nomarchy-theme-sync symlink for scripts and muscle memory.

Eval (mkFlake, doctor, lifecycle) still accepts theme-state.json; the
next write migrates to state.json and removes the legacy file.
Documented in MIGRATION.md; drop the CLI alias after release notes.

pkgs/nomarchy-control-center/nomarchy-control-center.sh

@@ -1,28 +1,28 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-# Nomarchy Control Center — TUI frontend over nomarchy-theme-sync and tools
+# Nomarchy Control Center — TUI frontend over nomarchy-state-sync and tools
 # Uses charmbracelet/gum for rendering.
 
 trap 'exit 0' SIGINT
 
 function get_state() {
-    nomarchy-theme-sync get "$1" 2>/dev/null || echo ""
+    nomarchy-state-sync get "$1" 2>/dev/null || echo ""
 }
 
 function set_state() {
-    nomarchy-theme-sync --quiet set "$1" "$2" --no-switch
+    nomarchy-state-sync --quiet set "$1" "$2" --no-switch
 }
 
 function first_boot() {
     gum style --border normal --margin "1" --padding "1 2" --border-foreground 212 "Welcome to Nomarchy!"
     
     echo "Pick a Theme Preset:"
-    themes=$(nomarchy-theme-sync list)
+    themes=$(nomarchy-state-sync list)
     chosen_theme=$(printf "%s" "$themes" | gum choose)
     if [ -n "$chosen_theme" ]; then
         echo "Applying theme $chosen_theme..."
-        nomarchy-theme-sync apply "$chosen_theme"
+        nomarchy-state-sync apply "$chosen_theme"
     fi
     
     if gum confirm "Enable auto-commit for your config? (settings changes + a sweep of pending edits before each rebuild)"; then
@@ -113,10 +113,10 @@ function appearance_menu() {
         choice=$(gum choose "Pick Theme" "Toggle Blur" "Set Gaps" "Back")
         case "$choice" in
             "Pick Theme")
-                themes=$(nomarchy-theme-sync list)
+                themes=$(nomarchy-state-sync list)
                 chosen=$(printf "%s" "$themes" | gum choose)
                 if [ -n "$chosen" ]; then
-                    nomarchy-theme-sync apply "$chosen"
+                    nomarchy-state-sync apply "$chosen"
                 fi
                 ;;
             "Toggle Blur")