feat(josh-sync): rename --subfolder now git mv's the actual directory

Previously --subfolder only repointed .josh-sync.yml, leaving the working
tree out of sync with the new path until a later filter-change
reconciliation happened to catch it. Now validates the old subfolder
exists and is tracked by git (proof it's actually managed by josh-sync)
and the new one doesn't already exist, then git mv's it — staged, not
committed, alongside the config edit. Idempotent on resume. Bumps to
v2.4.0.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TNXgcFWVgSh3wkQS55cCX6

lib/rename.sh

@@ -89,6 +89,43 @@ _rename_check_url_reachable() {
   return "$ok"
 }
 
+# ─── Subfolder Move ──────────────────────────────────────────────
+# Renaming a subfolder must move the actual directory in the monorepo
+# working tree via `git mv`, not just repoint the config — otherwise the
+# tree stops matching `.josh-sync.yml` until a later sync's filter-change
+# reconciliation happens to catch it. Both functions are idempotent against
+# a resumed run: if new_subfolder already exists and old_subfolder doesn't,
+# the move already happened, so there's nothing left to validate or do.
+
+# Usage: _rename_validate_subfolder_move <old_subfolder> <new_subfolder>
+_rename_validate_subfolder_move() {
+  local old_subfolder="$1" new_subfolder="$2"
+
+  if [ -e "$new_subfolder" ] && [ ! -e "$old_subfolder" ]; then
+    return 0
+  fi
+
+  [ -e "$old_subfolder" ] || die "Old subfolder '${old_subfolder}' does not exist in the working tree"
+  [ -n "$(git ls-files -- "$old_subfolder")" ] \
+    || die "Old subfolder '${old_subfolder}' has no files tracked by git — not managed by josh-sync"
+  [ ! -e "$new_subfolder" ] || die "New subfolder '${new_subfolder}' already exists — refusing to overwrite"
+}
+
+# Usage: _rename_move_subfolder <old_subfolder> <new_subfolder>
+_rename_move_subfolder() {
+  local old_subfolder="$1" new_subfolder="$2"
+
+  if [ -e "$new_subfolder" ] && [ ! -e "$old_subfolder" ]; then
+    log "INFO" "Subfolder already moved to '${new_subfolder}' — skipping git mv"
+    return 0
+  fi
+
+  mkdir -p "$(dirname "$new_subfolder")"
+  git mv "$old_subfolder" "$new_subfolder" \
+    || die "Failed to git mv '${old_subfolder}' -> '${new_subfolder}'"
+  log "INFO" "Moved ${old_subfolder} -> ${new_subfolder} (git mv, uncommitted)"
+}
+
 # ─── Stale Import-Branch Warning (best-effort, never fails) ────────
 # Onboarding's initial_import (lib/sync.sh) pushes staging branches named
 # auto-sync/import-<target>-<timestamp> to the MONOREPO. These are normally
@@ -223,6 +260,10 @@ rename_target() {
     [ -z "$existing" ] || die "State already exists for target '${new_name}' on ${STATE_BRANCH} — refusing to overwrite. Resolve manually (e.g. 'josh-sync state reset ${new_name} <branch>') before retrying."
   fi
 
+  if [ "$subfolder_changed" = true ]; then
+    _rename_validate_subfolder_move "$old_subfolder" "$new_subfolder"
+  fi
+
   if [ "$dry_run" = true ]; then
     log "INFO" "--dry-run: no changes written"
     return 0
@@ -235,6 +276,10 @@ rename_target() {
     [ "$confirm" = "y" ] || [ "$confirm" = "Y" ] || die "Aborted"
   fi
 
+  if [ "$subfolder_changed" = true ]; then
+    _rename_move_subfolder "$old_subfolder" "$new_subfolder"
+  fi
+
   if [ "$already_configured" != true ]; then
     log "INFO" "Updating ${config_file}..."
     # mikefarah/yq (v4, Go) has no jq-style --arg; pass values via env vars and