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-doctor/nomarchy-doctor.sh

@@ -67,21 +67,33 @@ for mp in / /boot /nix; do
 done
 
 # ── the flake + state file ───────────────────────────────────────────
-if [ -f "$flake/theme-state.json" ]; then
-  if jq empty "$flake/theme-state.json" 2>/dev/null; then
-    ok "theme-state.json parses"
+# #107: prefer state.json; theme-state.json still counts until migrated.
+state_file=
+if [ -f "$flake/state.json" ]; then
+  state_file="$flake/state.json"
+elif [ -f "$flake/theme-state.json" ]; then
+  state_file="$flake/theme-state.json"
+fi
+if [ -n "$state_file" ]; then
+  state_base=$(basename "$state_file")
+  if jq empty "$state_file" 2>/dev/null; then
+    ok "$state_base parses"
   else
-    bad "theme-state.json is not valid JSON (rebuilds will fail)" \
-        "nomarchy-theme-sync validate  (names the spot; fix it, or re-apply a theme)"
+    bad "$state_base is not valid JSON (rebuilds will fail)" \
+        "nomarchy-state-sync validate  (names the spot; fix it, or re-apply a theme)"
   fi
-  if git -C "$flake" ls-files --error-unmatch theme-state.json >/dev/null 2>&1; then
-    ok "theme-state.json is git-tracked"
+  if git -C "$flake" ls-files --error-unmatch "$state_base" >/dev/null 2>&1; then
+    ok "$state_base is git-tracked"
   else
-    bad "theme-state.json is NOT git-tracked (flake evaluation can't see it)" \
-        "git -C $flake add theme-state.json"
+    bad "$state_base is NOT git-tracked (flake evaluation can't see it)" \
+        "git -C $flake add $state_base"
+  fi
+  if [ "$state_base" = "theme-state.json" ]; then
+    warn "state file still named theme-state.json — run any menu write or" \
+         "nomarchy-state-sync set … to migrate to state.json"
   fi
 else
-  skip "theme-state.json (no flake checkout at $flake)"
+  skip "state.json (no flake checkout at $flake)"
 fi
 
 if [ -d "$flake/.git" ]; then