Fixes #9: Parser performance optimizations

- Pre-compile all regex patterns as module-level constants in parser.js and jsonRepair.js
- Add format detection caching (lastDetectedFormat, formatCacheHits) to skip redundant checks
- Add clearFormatCache() export for cache invalidation
- Add comprehensive test suite (33 tests) for parser and jsonRepair modules
- Fix regex escaping in dynamic patterns (statRegex, fieldRegex)
- Improve toFieldKey() regex specificity

package.json

@@ -6,6 +6,7 @@
   "type": "module",
   "scripts": {
     "build:css": "node scripts/build-css.js",
+    "test": "jest",
     "validate_locale": "node src/i18n/validator.js --watch",
     "validate_locale_once": "node src/i18n/validator.js"
   },
@@ -13,9 +14,12 @@
   "author": "",
   "license": "MIT",
   "devDependencies": {
+    "@babel/core": "^8.0.1",
+    "@babel/preset-env": "^8.0.2",
+    "@jest/globals": "^30.4.1",
     "chokidar": "^5.0.0",
     "fs-extra": "^11.3.3",
-    "glob": "^13.0.6"
-  },
-  "dependencies": {}
+    "glob": "^13.0.6",
+    "jest": "^30.4.2"
+  }
 }