feat(code): add /code:sync for dependent module sync (#119)

Add sync command that:
- Finds dependent modules from repos.yaml
- Updates composer.json with new version
- Supports --dry-run for preview
- Auto-detects current module from directory

Migrated from core-claude PR #63.

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

claude/code/commands/sync.md

@@ -0,0 +1,23 @@
+---
+name: sync
+description: Sync changes across dependent modules
+args: <module_name> [--dry-run]
+---
+
+# Sync Dependent Modules
+
+When changing a base module, this command syncs the dependent modules.
+
+## Usage
+
+```
+/code:sync                # Sync all dependents of current module
+/code:sync core-tenant    # Sync specific module
+/code:sync --dry-run      # Show what would change
+```
+
+## Action
+
+```bash
+"${CLAUDE_PLUGIN_ROOT}/scripts/sync.sh" "$@"
+```

claude/code/scripts/sync.sh

@@ -0,0 +1,56 @@
+#!/bin/bash
+
+dry_run=false
+target_module=""
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --dry-run)
+      dry_run=true
+      shift
+      ;;
+    *)
+      target_module="$1"
+      shift
+      ;;
+  esac
+done
+
+if [ ! -f "repos.yaml" ]; then
+    echo "Error: repos.yaml not found"
+    exit 1
+fi
+
+if [ -z "$target_module" ]; then
+    # Detect from current directory
+    target_module=$(basename "$(pwd)")
+fi
+
+echo "Syncing dependents of $target_module..."
+
+# Get version from composer.json
+version=$(jq -r '.version // "1.0.0"' "${target_module}/composer.json" 2>/dev/null || echo "1.0.0")
+
+# Find dependents from repos.yaml
+dependents=$(yq -r ".repos | to_entries[] | select(.value.depends[]? == \"$target_module\") | .key" repos.yaml 2>/dev/null)
+
+if [ -z "$dependents" ]; then
+    echo "No dependents found for $target_module"
+    exit 0
+fi
+
+echo "Dependents:"
+for dep in $dependents; do
+    echo "├── $dep"
+    if [ "$dry_run" = true ]; then
+        echo "│   └── [dry-run] Would update host-uk/$target_module to v$version"
+    else
+        composer_file="${dep}/composer.json"
+        if [ -f "$composer_file" ]; then
+            jq --arg pkg "host-uk/$target_module" --arg ver "$version" \
+                '.require[$pkg] = $ver' "$composer_file" > "$composer_file.tmp" && \
+                mv "$composer_file.tmp" "$composer_file"
+            echo "│   └── Updated composer.json"
+        fi
+    fi
+done