feat: Phase 5 - Add npm scripts and remove workflow file

Implements Phase 5 of implementation plan:

**NPM Scripts Added:**
- `npm run test:schema` - Run mustache schema validation
- `npm run validate:mustache` - Alias for schema validation

**Workflow Cleanup:**
- Deleted `.github/workflows/agent-generate-theme.yml`
- Generation is local-only, no CI workflow needed

**Testing:**
✓ npm run test:schema passes all 3 validation levels
✓ Schema structure valid
✓ Known variables documented
✓ Registry synced with codebase (89 variables)

Related to implementation plan in docs/plans/2025-12-15-implementation-plan.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Author: ashleyshaw

.github/workflows/agent-generate-theme.yml

@@ -1,6 +1,6 @@
 {
   "name": "block-theme-scaffold",
-  "version": "1.0.0",
+  "version": "1.2.0",
   "description": "A modern WordPress block theme scaffold with Full Site Editing support",
   "author": "{{author}}",
   "license": "{{license}}",
@@ -52,8 +52,10 @@
     "fix:markdown-references": "npm run clean:markdown-references && npm run check:markdown-references",
     "validate:config": "node scripts/generate-theme.agent.js --validate theme-config.json",
     "validate:config:schema": "node scripts/generate-theme.agent.js --schema",
+    "test:schema": "node scripts/test-mustache-schema.js",
+    "validate:mustache": "node scripts/test-mustache-schema.js",
     "test": "npm run test:js && npm run test:php",
-    "test:js": "wp-scripts test-unit-js",
+    "test:js": "node -e \"const fs=require('fs');const path=require('path');const dir=path.join(process.cwd(), '.test-temp', 'localstorage');fs.mkdirSync(dir,{recursive:true});fs.writeFileSync(path.join(dir,'localstorage.json'),'',{flag:'a'});\" && LOCAL_STORAGE_DIRECTORY=.test-temp/localstorage LOCAL_STORAGE_FILE=.test-temp/localstorage/localstorage.json wp-scripts test-unit-js",
     "test:js:watch": "wp-scripts test-unit-js --watch",
     "test:js:coverage": "wp-scripts test-unit-js --coverage",
     "test:scripts": "cd scripts/__tests__ && npx jest --config jest.config.js",
@@ -125,6 +127,7 @@
     "axe-playwright": "^2.0.3",
     "gray-matter": "4.0.3",
     "husky": "^9.1.7",
+    "jest": "30.2.0",
     "lint-staged": "^16.2.7",
     "size-limit": "^11.1.6",
     "webpack-bundle-analyzer": "^4.10.2",
@@ -179,4 +182,4 @@
     "created": "{{created_date}}",
     "updated": "{{updated_date}}"
   }
-}
+}