Add --force flag to reverse sync

Bypasses the PR step and force-pushes the subrepo's state directly onto
the monorepo branch. Also skips the skip-dirty guard. Only valid with
--reverse. Returns status "forced".

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

bin/josh-sync

@@ -88,6 +88,7 @@ Global flags:
 Sync flags:
   --forward         Forward only (mono → subrepo)
   --reverse         Reverse only (subrepo → mono)
+  --force           Force-push subrepo state to mono branch (--reverse only, skips PR)
   --target NAME     Filter to target(s) — comma-separated for multiple (env: JOSH_SYNC_TARGET)
   --branch BRANCH   Filter to one branch
 
@@ -108,6 +109,7 @@ cmd_sync() {
   local filter_target="${JOSH_SYNC_TARGET:-}"
   local filter_branch=""
   local config_file=".josh-sync.yml"
+  local force_flag=false
 
   while [ $# -gt 0 ]; do
     case "$1" in
@@ -117,10 +119,18 @@ cmd_sync() {
       --branch)  filter_branch="$2"; shift 2 ;;
       --config)  config_file="$2"; shift 2 ;;
       --debug)   export JOSH_SYNC_DEBUG=1; shift ;;
+      --force)   force_flag=true; shift ;;
       *) die "Unknown flag: $1" ;;
     esac
   done
 
+  if [ "$force_flag" = true ] && [ "$direction" != "reverse" ]; then
+    die "--force requires --reverse"
+  fi
+  if [ "$force_flag" = true ]; then
+    export SYNC_REVERSE_FORCE=1
+  fi
+
   parse_config "$config_file"
 
   # Forward sync
@@ -263,6 +273,9 @@ _sync_direction() {
         log "WARN" "Trees differ but no human commits — skipping state update (will retry)"
         continue
       fi
+      if [ "$result" = "forced" ]; then
+        log "WARN" "Target ${target_name}, branch ${branch}: force-pushed subrepo directly to mono — DESTRUCTIVE"
+      fi
 
       # Update state (only on success)
       local new_state