Clean up backend and web-player leftovers

Remove dead scaffold/config cruft and stale references left over from
recent refactors: dotnet's WebApi.http template file, the AppSettings
PascalCase/Dockerfile workaround (renamed to appsettings.json to match
convention), empty directories left behind by the auth-route and
folder-structure moves, a stale ESLint ignore, and the now-fully-applied
frontend refactor plan doc.

docs/development.md

@@ -134,10 +134,10 @@ omits the `<Error>` list when there are no errors, unlike AWS S3), and
 (load → modify → save) because it ran before EF had detected the pending
 changes.
 
-## Config (AppSettings)
+## Config (appsettings)
 
-Convention: `AppSettings.json` is the template, with empty or neutral
-values; `AppSettings.Development.json` has the real dev values; in Docker
+Convention: `appsettings.json` is the template, with empty or neutral
+values; `appsettings.Development.json` has the real dev values; in Docker
 everything is overridden with environment variables (`Section__Key`) from
 `deploy/compose.yml`. To run `Musify.Api` from the IDE, the `Authentication`
 values go into user-secrets (not the repo). Copy them from `deploy/.env`

docs/media-processing.md

@@ -36,7 +36,7 @@ Grouped by area:
 
 ## What the Worker needs configured
 
-The Worker registers: storage (S3), transcoder (ffmpeg), pictures, the DB, the MassTransit consumers, and the upload-intent jobs. Its `AppSettings` needs the right sections: `Bucket` (= `webapi-storage`, same as the API), `PlayList`, `Track`, `MassTransit`, `AudioTranscoder`, `UploadIntent`, `Workers` (temp directory), `InfrastructureStorage`, `Database`.
+The Worker registers: storage (S3), transcoder (ffmpeg), pictures, the DB, the MassTransit consumers, and the upload-intent jobs. Its `appsettings` needs the right sections: `Bucket` (= `webapi-storage`, same as the API), `PlayList`, `Track`, `MassTransit`, `AudioTranscoder`, `UploadIntent`, `Workers` (temp directory), `InfrastructureStorage`, `Database`.
 
 ## Background jobs