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/MIGRATION.md

@@ -169,7 +169,7 @@ ryzenadj)**, **no Secure Boot**, and the **stateVersion override**.
   nomarchy.hardware.amd.enable = true;       # amd-pstate + radeonsi VA-API
   # nomarchy.hardware.amd.rocm.enable = true; # opt-in GPU compute (multi-GB)
 
-  # Auto-login is NOT set here: it lives in theme-state.json
+  # Auto-login is NOT set here: it lives in state.json
   # (settings.greeter.autoLogin) so System › Auto-login can move it — a line
   # here would outrank the state and pin it. Turn it on after the first boot
   # with `nomarchy-autologin on` (what nomarchy-install seeds on encrypted
@@ -206,9 +206,9 @@ emacs setup).
 }
 ```
 
-### `theme-state.json`
+### `state.json`
 
-Copy the template's `theme-state.json` (or let `nomarchy-menu theme` write
+Copy the template's `state.json` (or let `nomarchy-menu theme` write
 it after the switch). Your old `nomarchy-state.nix` prototype (schema
 `nomarchy.theme = "nord"` …) is **retired** — the current distro uses this
 JSON. `nord` is a shipped Nomarchy theme, so you lose nothing.
@@ -247,7 +247,7 @@ radeonsi), display brightness.
 You should also get a one-shot **You're set** toast (menu / themes /
 keys). If it never appears: `systemctl --user status nomarchy-first-boot`
 and re-try with
-`nomarchy-theme-sync set settings.firstBootShown false --no-switch`
+`nomarchy-state-sync set settings.firstBootShown false --no-switch`
 then log out/in.
 
 If anything is wrong: **reboot → old generation.** Nothing is committed as
@@ -261,7 +261,7 @@ default yet.
   power‑profile icons open the power menu. Your ryzenadj scripts are gone;
   if you miss a specific TDP behaviour, that's a follow‑up, not a blocker.
 - **Theme:** `nomarchy-menu theme` → pick a preset (writes
-  `theme-state.json`).
+  `state.json`).
 - **Snapshots:** `nomarchy-menu` → System → Snapshots should see your
   existing `@snapshots` subvolume.
 - **Fingerprint:** `fingerprint.enable = true` only starts **fprintd**
@@ -446,6 +446,25 @@ just reports that no swap is configured.
 
 ---
 
+## State file rename (`theme-state.json` → `state.json`, #107)
+
+The machine flake's git-tracked state file is **`state.json`** (appearance +
+menu settings). Older checkouts may still have `theme-state.json`.
+
+- **Eval:** `lib.mkFlake` and the reader accept either name (prefer
+  `state.json`).
+- **Write:** `nomarchy-state-sync` (and the menu) always write `state.json`
+  and remove a leftover `theme-state.json` so you never have two sources.
+- **CLI:** `nomarchy-state-sync` is the real name; `nomarchy-theme-sync`
+  remains a symlink for scripts and muscle memory. Drop the alias after the
+  next stable release notes call it out.
+
+No action required on pull: the next theme apply or menu write migrates you.
+To migrate by hand: `mv theme-state.json state.json && git add state.json`
+(and `git rm theme-state.json` if it was tracked).
+
+---
+
 ## TuringMachine — the decisions, at a glance
 
 | Item | Choice |