Use String.raw and RegExp.exec, add prefer-regexp-exec oxlint rule

Replace escaped backslash in template literal with String.raw in
auto-number.ts. Use RegExp#exec() instead of String#match() in
bestiary-adapter.ts. Enable typescript/prefer-regexp-exec in oxlint
for automated enforcement.

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

.oxlintrc.json

@@ -5,6 +5,7 @@
 	"rules": {
 		"typescript/no-unnecessary-type-assertion": "error",
 		"typescript/no-deprecated": "warn",
+		"typescript/prefer-regexp-exec": "error",
 		"unicorn/prefer-string-replace-all": "error",
 		"unicorn/prefer-string-raw": "error",
 		"jest/expect-expect": [