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-state-sync/default.nix

@@ -0,0 +1,54 @@
+{ lib
+, stdenvNoCC
+, python3
+, makeWrapper
+, awww
+, libnotify
+, git
+  # Shipped theme presets, baked into the package as a fallback so
+  # `list`/`apply` work even when $NOMARCHY_PATH has no themes/ dir.
+, themesDir ? null
+}:
+
+stdenvNoCC.mkDerivation {
+  pname = "nomarchy-state-sync";
+  version = "0.5.0";
+
+  src = ./.;
+
+  nativeBuildInputs = [ makeWrapper ];
+  buildInputs = [ python3 ];
+
+  installPhase = ''
+    runHook preInstall
+
+    install -Dm755 nomarchy-state-sync.py $out/bin/nomarchy-state-sync
+    patchShebangs $out/bin/nomarchy-state-sync
+
+    ${lib.optionalString (themesDir != null) ''
+      mkdir -p $out/share/nomarchy
+      cp -r ${themesDir} $out/share/nomarchy/themes
+    ''}
+
+    # Stdlib-only Python. home-manager is deliberately NOT wrapped in —
+    # the rebuild must use the user's own home-manager from their PATH.
+    wrapProgram $out/bin/nomarchy-state-sync \
+      --prefix PATH : ${lib.makeBinPath [ awww libnotify git ]} \
+      ${lib.optionalString (themesDir != null)
+        "--set NOMARCHY_DEFAULT_THEMES $out/share/nomarchy/themes"}
+
+    # #107: old CLI name kept as a symlink so muscle memory and scripts
+    # survive a pull (drop after the next stable release notes say so).
+    # After wrapProgram so it points at the wrapper, not the raw script.
+    ln -s nomarchy-state-sync $out/bin/nomarchy-theme-sync
+
+    runHook postInstall
+  '';
+
+  meta = {
+    description = "Nomarchy state writer + Home Manager rebuild dispatcher";
+    license = lib.licenses.mit;
+    mainProgram = "nomarchy-state-sync";
+    platforms = lib.platforms.linux;
+  };
+}