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.

docs/OMARCHY.md

@@ -81,11 +81,11 @@ Both distros reskin everything from one place. In Nomarchy:
 - **`SUPER+T`** (or `nomarchy-menu theme`) — pick from 24 presets with live
   previews; it rebuilds and applies to Hyprland, Waybar, the terminal,
   btop and GTK/Qt at once.
-- Or from a shell: `nomarchy-theme-sync apply <slug>` (e.g. `gruvbox`,
+- Or from a shell: `nomarchy-state-sync apply <slug>` (e.g. `gruvbox`,
   `rose-pine`, `nord`).
 - Tweak gaps / rounding / fonts / opacity / icon pack without leaving the
   theme system — see [OVERRIDES.md](OVERRIDES.md). One git-tracked JSON
-  (`theme-state.json`) is the single source of truth.
+  (`state.json`) is the single source of truth.
 
 ---