feat(design): every button on its family, the chip primitive, the lint rule (E28 S3b2)

The second half of the button sweep: the remaining hand-rolled buttons in
feature components, the design lab and the components/ui composites now
stand on Button, IconButton, Pressable, Chip or DragHandle.

- Chip + DismissibleChip (filter / token / tag / suggest / ghost, 24px
  floor, 44 on touch) replace five chip geometries; FilterChipGroup
  renders Chips; overflow lanes measure a mirror painted by chipClass.
- The Plex control row is IconButton's player rung (36, 20px glyph,
  round, overlay; 44 on touch); the YT modal bar is on the sm rung with
  pressed cycle toggles and names that survive a folded label.
- New variants: IconButton ghost-accent, danger-soft; Button warn on a
  new state-warn utility. The .btn-{tone} recipes and btnCls are gone.
- Fixed on the way: membership rows (collection editor, Plex playlist
  add) announce checked/mixed; a one-letter tag chip was 21px wide;
  descriptionLinks moved out of lib/ (it renders components).
- local/button-primitive: a raw <button>/<FocusSafeButton> outside the
  control-primitive files is a lint error (contract-tested, seen red).

frontend/src/components/UploadDialog.tsx

@@ -14,7 +14,7 @@ import { navigateTo } from "../lib/nav";
 import { formatBytes } from "../lib/format";
 import { DISPLAY_NAME_MAX } from "../lib/api/downloads";
 import { inputCls } from "./ui/form";
-import { FocusSafeButton } from "./ui/FocusSafeButton";
+import { Pressable } from "./ui/Pressable";
 
 // Local-file ingest (E7 S5c · D5-A). A general upload — ANY file type, no format list: media
 // (video/audio) joins the library with the full function set, a generic file is download-only. The
@@ -102,8 +102,8 @@ export default function UploadDialog({ onClose }: { onClose: () => void }) {
       <p className="text-sm text-muted mb-4">{t("downloads.upload.hint")}</p>
 
       {/* Drop zone doubles as the picker trigger — a click anywhere opens the native file dialog. */}
-      <FocusSafeButton
-        type="button"
+      <Pressable
+        align="center"
         onClick={pick}
         onDragEnter={(e) => {
           e.preventDefault();
@@ -158,7 +158,7 @@ export default function UploadDialog({ onClose }: { onClose: () => void }) {
             </span>
           </>
         )}
-      </FocusSafeButton>
+      </Pressable>
       <input
         ref={inputRef}
         type="file"