Upgrade webpack from 3.9.1 to 5.100.2

- Update webpack to v5.100.2 with webpack-cli v5.1.4
- Replace deprecated uglifyjs-webpack-plugin with terser-webpack-plugin
- Replace deprecated eslint-loader with eslint-webpack-plugin
- Update ESLint to v9.15.0 and eslint-config-prettier to v9.1.0
- Update webpack config for v5 syntax (mode, optimization, clean output)
- Remove webpack version limits from dependabot config

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: bfirsh

.github/dependabot.yml

@@ -5,8 +5,3 @@ updates:
   schedule:
     interval: weekly
   open-pull-requests-limit: 10
-  ignore:
-  - dependency-name: webpack
-    versions:
-    - "< 5"
-    - ">= 4.0.a"