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.

modules/home/default.nix

@@ -6,7 +6,7 @@
 {
   imports = [
     ./options.nix   # the nomarchy.* option surface
-    ./theme.nix     # ingests theme-state.json, owns the live-sync hooks
+    ./theme.nix     # ingests state.json, owns the live-sync hooks
     ./stylix.nix    # GTK/Qt/cursor/fonts from the same JSON
     ./hyprland.nix
     ./waybar.nix
@@ -106,8 +106,8 @@
     # (system nixpkgs.config alone does not cover those entry points).
     NIXPKGS_ALLOW_UNFREE = "1";
 
-    # Where the Nomarchy flake (and therefore theme-state.json) lives on
-    # disk. nomarchy-theme-sync writes its state here; rebuilds read from
+    # Where the Nomarchy flake (and therefore state.json) lives on
+    # disk. nomarchy-state-sync writes its state here; rebuilds read from
     # here. Clone/symlink your flake to this path.
     NOMARCHY_PATH = "$HOME/.nomarchy";
   };