Replace rails-assets.org gems with yarn/npm packages

[Copilot]

Summary of changes

• Remove source 'https://rails-assets.org' block and all 6 rails-assets-* gems from Gemfile/Gemfile.lock
• Add package.json with npm equivalents; generate yarn.lock via yarn install
• Configure Sprockets to find npm packages by adding specific node_modules/ subdirectories to config.assets.paths in config/initializers/assets.rb
• Update two //= require names in application.js and one @import in application.scss to match actual npm dist filenames (eonasdan-bootstrap-datetimepicker → bootstrap-datetimepicker, devbridge-autocomplete → jquery.autocomplete)
• Add node_modules/ to .gitignore

Motivation and context

#1253

rails-assets.org is defunct — its gems cannot be installed in fresh environments, blocking deployment. This migrates those 6 frontend packages to yarn/npm while keeping the Sprockets asset pipeline intact.

The Sprockets integration works by registering specific dist subdirectories from node_modules/ as asset load paths:

# config/initializers/assets.rb
%w[
  clipboard/dist
  devbridge-autocomplete/dist
  eonasdan-bootstrap-datetimepicker/src/js
  eonasdan-bootstrap-datetimepicker/build/css
  markdown-it/dist
  moment
  select2/dist/js
  select2/dist/css
].each do |path|
  Rails.application.config.assets.paths << Rails.root.join("node_modules/#{path}")
end

Existing //= require and @import directives continue to work; only two names changed to align with how the npm packages name their dist files.

Screenshots

N/A

Checklist

• I have read and followed the CONTRIBUTING guide.
• I confirm that I have the authority necessary to make this contribution on behalf of its copyright owner and agree
  to license it to the TeSS codebase under the
  BSD license.

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[Copilot]

Pull request overview

This PR migrates frontend dependencies away from the defunct rails-assets.org gem source to Yarn/NPM while keeping the Rails/Sprockets asset pipeline.

Changes:

• Remove rails-assets-* gems and the rails-assets.org Gemfile source; add package.json + yarn.lock for the equivalent JS/CSS packages.
• Configure Sprockets to load selected node_modules/ subdirectories and update JS/CSS manifests to match NPM distro filenames.
• Update Docker/CI/docs to install Yarn dependencies and ignore node_modules/.

Reviewed changes

Copilot reviewed 10 out of 13 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
yarn.lock	Adds Yarn v1 lockfile pinning JS dependency tree.
package.json	Defines NPM dependencies replacing rails-assets gems.
docs/production.md	Documents installing npm/yarn and running yarn install for production setup.
docs/install.md	Documents npm/yarn as prerequisites and Yarn install steps.
config/initializers/assets.rb	Adds node_modules subpaths to Sprockets asset load paths.
app/assets/stylesheets/application.scss	Updates datetimepicker import to bootstrap-datetimepicker.
app/assets/javascripts/application.js	Updates require names for datetimepicker and autocomplete packages.
Gemfile.lock	Removes rails-assets source and rails-assets gem dependencies.
Gemfile	Removes rails-assets.org source block and rails-assets gems.
Dockerfile	Installs npm/yarn and runs yarn install during image build.
.gitignore	Ignores node_modules/.
.github/workflows/test.yml	Adds yarn install step before running Rails tests.
.github/workflows/deployment-checks.yml	Adds yarn install step before assets:precompile.

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