This updates the signature preferences connector to use modern Ember patterns and the new plugin API.
Changes:
- Convert to Glimmer component with `@service` injection
- Replace classic `<Input>` with native `<input>` and `{{on}}` modifier
- Use new `api.addSaveableCustomFields("profile")` API instead of `modifyClass save()` override
- Remove dead `@showUploadModal` argument from `DEditor`
- Add CSS to hide preview panel and match bio editor width
The `modifyClass` pattern for saving `custom_fields` was broken because `saveAttrNames` is now a getter that returns a fresh array on each call, so pushing to it in `save()` had no effect. The new `addSaveableCustomFields` API uses value transformers to properly add "`custom_fields`" to the save attributes.
cf. https://github.com/discourse/discourse/pull/36757
Remove deprecated discourse.post-stream-widget-overrides and associated legacy widget customizations.
This cleanup reduces technical debt, ensures future maintainability, and aligns with the latest framework improvements.
- Introduces a new `PostSignature` component to handle user signatures, ensuring compatibility with the Glimmer post stream.
- Updates initializers to integrate the new component and maintain compatibility with existing features.
- Cook on advanced mode is server side and properly cached now
- Remove deprecated dependencies on client-side code
Attention: Users on advanced mode from previous versions should re-enter
their signatures.