feat(design): a Plex title's one action list (C1) — the poster's "…", details and the pin in its menu (E28 S3e2)

Every Plex poster list (library, Discover rails, person, show, season, collection, Home's rails)
now opens one menu per list from the right-click, the long-press, Shift+F10 and the card's "…":
play/open, watched, add to playlist, media info, copy title, the pin (usePlexCardActions +
PlexMenu, replacing the pin-only PlexPinMenu). The card keeps its state at rest and shows
watched / add to playlist / "…" on its picture on hover (ui/reveal.ts, shared with the video
card); on touch the toggles are gone and a 44px "…" sits beside the title, while the watched pill
stays. The hover ⓘ left the card; an episode's add button moved from its caption to the hover
row. Seasons get their own short menu (open, watched, add, copy), labelled "Open season" (the
card's overlay said "Open show"). Related shows are ordinary poster cards now. A collection's
admin "Remove" X moved into its menu, still behind the confirmation. The collection grid is two
columns on a phone. The unused .reveal-idle rule is gone.

frontend/src/components/ui/reveal.ts

@@ -0,0 +1,8 @@
+// A card's hover chrome (E28 C1): shown when the card is hovered or holds keyboard focus on a mouse,
+// removed on touch (`.reveal-hover`, index.css), where the card offers the same actions through its
+// "…" beside the title. One string, so the video card and the Plex cards reveal the same way.
+export const HOVER_REVEAL =
+  "reveal-hover opacity-0 group-hover:opacity-100 group-focus-within:opacity-100 transition-opacity";
+
+/** What sits under that chrome at rest (a duration, a watched pill) steps aside while it shows. */
+export const HOVER_YIELD = "transition-opacity group-hover:opacity-0 group-focus-within:opacity-0";