style: remove eslint with frontend code removal ADR

- Add ADR for frontend code removal
- Drop eslint, as explained in the ADR

docs/concepts/frontend/javascript.rst

@@ -1,10 +1,16 @@
 JavaScript in edx-platform
 ==========================
 
+All frontend code (JavaScript) has been deprecated in edx-platform, in favor of
+MFEs. See ADR 0023-frontend-code-and-eslint-removal.rst for details.
+
+This documentation is being left in place until all of the JavaScript code
+has been removed.
+
 ES2015
 ------
 
-All new JavaScript code in edx-platform should be written in ES2015.
+All JavaScript code in edx-platform should be written in ES2015.
 ES2015 is not a framework or library -- rather, it is the latest and
 greatest revision of the JavaScript language itself, natively supported
 in all modern browsers and engines. Think of it as JavaScript's
@@ -34,13 +40,7 @@ Adding a New ES2015 Module
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Don't mix ES2015 and ES5 modules within directories. If necessary,
-create a new directory just for your new file. If you create a new
-directory, run the following from edx-platform root to copy over an
-appropriate eslint config:
-
-::
-
-    cp cms/static/js/features_jsx/.eslintrc.js path/to/your/directory
+create a new directory just for your new file.
 
 Give your new file an UpperCamelCase filename, such as
 ``MyAwesomeModule.js``. If it is a React module, use the ``.jsx``

docs/concepts/testing/testing.rst

@@ -303,8 +303,6 @@ We use several tools to analyze code quality. The full set of them is::
     make xsslint
     make pii_check
     make check_keywords
-    npm run lint
 
 Where ``$PATHS...`` is a list of folders and files to analyze, or nothing if
 you would like to analyze the entire codebase (which can take a while).
-

docs/decisions/0023-frontend-code-and-eslint-removal.rst

@@ -0,0 +1,48 @@
+Frontend code and ESLint removal
+################################
+
+Status
+******
+
+Accepted
+
+Context
+*******
+
+Over many years work has been underway to extract frontend code from
+edx-platform, to be replaced by MFEs.
+
+Additionally, as of March 2025, edx-platform had more than 700 violations in
+ESLint.
+
+For more details on the MFE replacement, see:
+
+- Top-level issue for edx-platform: https://github.com/openedx/edx-platform/issues/31620
+- The parent issue of the above issue, which includes IDA frontends: https://github.com/openedx/wg-frontend/issues/156
+- Details of the replacement MFEs are noted in the `MFE Rewrite Tracker`_.
+
+.. _MFE Rewrite Tracker: https://openedx.atlassian.net/wiki/spaces/COMM/pages/4262363137/MFE+Rewrite+Tracker
+
+Decision
+********
+
+Over these years of work, it was decided that all frontend code should
+ultimately be removed from edx-platform. Until this time, there has not yet
+been a single ADR or DEPR to capture this decision.
+
+This decision record is to document this past decision. It is ok to add
+additional links or details over time to clarify how this extraction will be
+accomplished, or to one day celebrate its completion.
+
+Additionally, it has been decided to preemptively remove ESLint. This will
+ensure that engineers can stay focused on higher priority work, rather than
+spending time fixing linting issues in JavaScript that will simply be removed.
+This removal is important because github has started posting these violations
+in github comments that make this work seem like a priority. At the very least,
+these are annoying messages that clutter up PRs.
+
+Consequences
+************
+
+We will continue to replace all frontend code in edx-platform with an
+appropriate set of MFEs.