[packages.dart] chore: migrate workspace to hermetic Bazel build environment

.bazelignore

@@ -0,0 +1,11 @@
+build
+.dart_tool
+.git
+.github
+.gitea
+.vscode
+.agents
+node_modules
+# Ignore nested package builds
+**/build
+**/.dart_tool

.github/dependabot.yml

@@ -29,3 +29,19 @@ updates:
     directory: "/packages/flutter_whatsnew"
     schedule:
       interval: "daily"
+
+  - package-ecosystem: "pub"
+    directory: "/packages/app_review"
+    schedule:
+      interval: "daily"
+
+  - package-ecosystem: "pub"
+    directory: "/packages/undo"
+    schedule:
+      interval: "daily"
+
+  - package-ecosystem: "gitsubmodule"
+    directory: "/"
+    schedule:
+      interval: "daily"
+