feat(state): opt-in auto-commit of state mutations (Phase 4)

settings.autoCommit — toggled from System › Auto-commit (self-gated on
the flake being a git repo) — makes every nomarchy-theme-sync apply/set
also git-commit theme-state.json in the downstream flake, so settings
history is `git log`. Off by default.

Design: the flag is live-read by the tool on each write (nothing in Nix
consumes it → instant toggle, no rebuild, no new option); the commit is
pathspec-limited to theme-state.json so unrelated dirty files are never
swept up; it fires when the flag is on before OR after the write, so
the disable-toggle itself lands in history; same-value writes no-op
(diff against HEAD); missing git identity falls back to
Nomarchy <nomarchy@localhost>; `bg next` is deliberately excluded.

Rider fix: `get` now prints booleans JSON-style (true, not Python's
True) — un-sticking the System menu's "Auto timezone (on/off)" label,
whose `= true` comparison could never match. All shell consumers
already normalise true|True, so no other behavior change.

Verified: V0 (py_compile, nix flake check) + V1 (HM generation builds,
generated nomarchy-menu passes bash -n, wiring present in the rendered
script) + a 7-assertion sandbox-repo round-trip covering enable/set/
same-value/disable/post-disable/apply paths and the identity fallback.
Remaining: on-machine check queued in agent/HARDWARE-QUEUE.md.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

modules/home/rofi.nix

@@ -387,6 +387,22 @@ ${themeRows}
           || { notify-send "Auto timezone" "Unavailable on this machine."; exit 0; }
         exec ${cfg.terminal} -e nomarchy-autotimezone toggle ;;
 
+      autocommit)
+        # Toggle opt-in auto-commit: every menu/theme mutation also commits
+        # theme-state.json (that file only) in the downstream flake, so
+        # settings history is `git log`. Nothing in Nix consumes the flag —
+        # the tool reads the live state on each write — so the toggle is
+        # instant, no rebuild. The off-write commits too (the tool fires
+        # when the flag was on before OR after), keeping history consistent.
+        if [ "$(nomarchy-theme-sync get settings.autoCommit 2>/dev/null)" = true ]; then
+          nomarchy-theme-sync --quiet set settings.autoCommit false --no-switch
+          notify-send "Auto-commit" "Off — menu changes stay uncommitted in your flake."
+        else
+          nomarchy-theme-sync --quiet set settings.autoCommit true --no-switch
+          notify-send "Auto-commit" "On — each change commits theme-state.json in your flake."
+        fi
+        exit 0 ;;
+
       snapshot)
         # btrfs-assistant 2.2 segfaults on 26.05 (libbtrfsutil ABI), so launch
         # the keyboard-driven snapper browser instead: a terminal running it
@@ -443,6 +459,12 @@ ${themeRows}
           then row "Auto timezone (on)"  preferences-system-time
           else row "Auto timezone (off)" preferences-system-time
           fi
+          if [ -e "''${NOMARCHY_PATH:-$HOME/.nomarchy}/.git" ]; then
+            if [ "$(nomarchy-theme-sync get settings.autoCommit 2>/dev/null)" = true ]
+            then row "Auto-commit (on)"  git
+            else row "Auto-commit (off)" git
+            fi
+          fi
           command -v nomarchy-snapshots >/dev/null 2>&1 && row "Snapshots" timeshift
           if [ -e "''${bats[0]}" ] && command -v powerprofilesctl >/dev/null 2>&1; then
             row "Power profile" preferences-system-power
@@ -460,6 +482,7 @@ ${themeRows}
           *"Do Not Disturb"*) exec "$0" dnd ;;
           *"Night light"*)    exec "$0" nightlight ;;
           *"Auto timezone"*)  exec "$0" autotimezone ;;
+          *"Auto-commit"*)    exec "$0" autocommit ;;
           *Snapshots*)        exec "$0" snapshot ;;
           *"Power profile"*)  exec "$0" power-profile ;;
         esac ;;
@@ -486,7 +509,7 @@ ${themeRows}
         esac ;;
 
       *)
-        echo "usage: nomarchy-menu [tools|system|power|power-profile|theme|clipboard|calc|files|emoji|web|network|bluetooth|audio|display|printers|capture|keybinds|ask|dnd|nightlight|autotimezone|vpn|snapshot]" >&2
+        echo "usage: nomarchy-menu [tools|system|power|power-profile|theme|clipboard|calc|files|emoji|web|network|bluetooth|audio|display|printers|capture|keybinds|ask|dnd|nightlight|autotimezone|autocommit|vpn|snapshot]" >&2
         exit 64 ;;
     esac
   '';