fix: align webpack lower bound to >=5.76.0 across all workspaces

Tightens the webpack override and pro dummy constraints from >=5.0.0 to
>=5.76.0, matching the main dummy and shakapacker's peer requirement of
^5.76.0. No functional change — pnpm already resolves to 5.105.2.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: justin808

package.json

@@ -156,7 +156,7 @@
       "picomatch@<2.3.2": ">=2.3.2 <3",
       "picomatch@>=4.0.0 <4.0.4": ">=4.0.4 <5",
       "yaml@>=1.0.0 <1.10.3": ">=1.10.3 <2",
-      "webpack": ">=5.0.0 <5.106.0"
+      "webpack": ">=5.76.0 <5.106.0"
     }
   }
 }

pnpm-lock.yaml

@@ -69,7 +69,7 @@
     "terser-webpack-plugin": "5",
     "turbolinks": "^5.2.0",
     "url-loader": "^4.1.1",
-    "webpack": ">=5.0.0 <5.106.0",
+    "webpack": ">=5.76.0 <5.106.0",
     "webpack-assets-manifest": "5",
     "webpack-manifest-plugin": "^2.0.4",
     "webpack-merge": "5"

react_on_rails_pro/spec/dummy/package.json

@@ -33,7 +33,7 @@
     "shakapacker": "9.6.1",
     "style-loader": "^4.0.0",
     "terser-webpack-plugin": "5",
-    "webpack": ">=5.0.0 <5.106.0",
+    "webpack": ">=5.76.0 <5.106.0",
     "webpack-assets-manifest": "5",
     "webpack-cli": "^6.0.1",
     "webpack-merge": "5"