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.

web-player/CLAUDE.md

@@ -46,14 +46,14 @@ npm run lint:tokens      # scripts/check-tokens.mjs, the design system guardrail
 
 ## Styles
 
-The design system lives in `src/routes/layout.css` (`@theme` tokens plus `@utility` recipes) and in `src/lib/theme/` (`theme.css` for the static neutrals, `tokens.ts` for the dynamic tokens that depend on the user's hue). `scripts/check-tokens.mjs` (run as `npm run lint:tokens`, part of `lint`) fails if `src/**/*.svelte` brings back what the refactor in `docs/frontend-refactor-plan.md` (parts P0 through P14) removed, so read that doc before adding an arbitrary value or a stock radius or size.
+The design system lives in `src/routes/layout.css` (`@theme` tokens plus `@utility` recipes) and in `src/lib/theme/` (`theme.css` for the static neutrals, `tokens.ts` for the dynamic tokens that depend on the user's hue). `scripts/check-tokens.mjs` (run as `npm run lint:tokens`, part of `lint`) fails on a stock radius, an `h-N w-N` pair, fractional quarter spacing, a literal hex/`rgba()`, or an arbitrary `-[…]` value outside its whitelist, so check that script before adding one.
 
 - **Radii:** always `rounded-tag/thumb/control/art/art-lg/panel/panel-lg` (or `rounded-full` for pills and circles). Never `rounded-sm/md/lg/xl/2xl/3xl` or a bare `rounded`.
 - **Square sizes:** use `size-*` instead of repeating `h-N w-N` (icons: `size-icon-xs/sm/md/lg/xl`; covers: `size-cover-xs` through `size-cover-hero`).
 - **Typography:** use the recipes `text-display-1/2/3/4`, `text-eyebrow`, `text-body`, `text-count`, with tracking through `tracking-display`/`tracking-eyebrow` rather than a loose `tracking-[…]`.
 - **Spacing:** stick to the Tailwind scale in `.5` steps and avoid quarters like `.25`/`.75`, unless the semantic token calls for it (for example `mb-4.5` in `SectionHeading`).
 - **Colors:** always use `--mf-*`/`text-*`/`bg-*`/`border-*` from `theme.css`/`tokens.ts`. Never a literal hex or `rgba()` inside a `.svelte` file; those literals only belong in `theme.css`/`tokens.ts` as the source of truth.
-- **Inline `style="…"` and arbitrary `-[…]` values:** only the ones whitelisted in section B.4 of `docs/frontend-refactor-plan.md` (the stagger variable `--i`, tile hue, menu position, dynamic widths and heights through `var(--mf-*)`, `text-[clamp(…)]`, `grid-cols-[auto_1fr]`, `max-h-[85dvh]`, and `vh` paddings for vertical centering). Everything else should become a token.
+- **Inline `style="…"` and arbitrary `-[…]` values:** only the ones whitelisted in `scripts/check-tokens.mjs` (the stagger variable `--i`, tile hue, menu position, progress width, `text-[clamp(…)]`, `leading-[…]` on login's display type, `grid-cols-[auto_1fr]`, `max-h-[85dvh]`, `my-`/`py-[Ndvh]` for vertical centering, `transition-[filter]` on genre tiles, and `bg-[image:var(--mf-*)]`). Everything else should become a token.
 - Reach for these base components before creating a new one: `Artwork`, `Avatar`, `ListRow`, `MediaIdentity`, `TrackList`, `MediaCard`, `PageHeader`, `ContextMenu`, `ConfirmDialog`, `PlayButton`, `Slider`, `Logo`, `Chip`, `SegmentedControl`, `CoverForm`.
 - Known and accepted gap (documented in `scripts/check-tokens.mjs`): icon `strokeWidth={n}` isn't unified yet. There are 13 different values spread across almost every component, and migrating them to `stroke-thin/regular/bold` recipes safely would require visually confirming that `lucide-svelte` actually respects `stroke-width` through CSS, so that was left out of the last pass.