fix(CssManager): Make CssManager a singleton and export the shared instance via getSingleton; update tests and dependencies

package.json

@@ -14,9 +14,9 @@
     "buildDocs": "tsdoc"
   },
   "devDependencies": {
-    "@git.zone/tsbuild": "^2.6.4",
-    "@git.zone/tsbundle": "^2.4.0",
-    "@git.zone/tstest": "^2.3.1",
+    "@git.zone/tsbuild": "^2.7.1",
+    "@git.zone/tsbundle": "^2.5.1",
+    "@git.zone/tstest": "^2.7.0",
     "@push.rocks/tapbundle": "^6.0.3",
     "@types/node": "^22.14.1"
   },
@@ -24,7 +24,7 @@
     "@design.estate/dees-domtools": "^2.3.3",
     "@push.rocks/isounique": "^1.0.5",
     "@push.rocks/smartrx": "^3.0.10",
-    "lit": "^3.3.0"
+    "lit": "^3.3.1"
   },
   "browserslist": [
     "last 1 chrome versions"