fix(e10): review round 1 — the boundary that did not bind, and 14 more

The epic-end review found 32 verified issues. This is the first fix round:
the three highs, the user-facing mediums, and the tests that were passing
for the wrong reason. Docs and the remaining low-severity tail are next.

The boundary rule was the worst of them. Both `no-restricted-imports`
regexes were written in plain "..." literals, where `\.` is an unknown
escape that collapses to the any-char `.` — so the rule read like a
boundary and matched far less than one. `../../lib/api` (the barrel every
feature component imports) and `../../components/Feed` (the same file
`../Feed` names) both sailed through a green gate. String.raw, a third
pattern for the second spelling, and a vitest over ESLint.lintText so a
rule that silently matches nothing can never look like a clean codebase
again.

closeThenNavigate waited for exactly one reclaim popstate. With a second
Back-closable layer still mounted — a palette opened over the player —
the navigation unmounted that layer too, and its reconcile backed over
the entry the navigation had just pushed: "go to Channels" closed the
player and landed on the feed. It now waits for the LAST programmatic
back, then adopts the entries the navigation buried, and falls back after
250ms rather than hanging if no popstate is ever coming.

The rail's inline rename died on arrival. With no domReference, floating-
ui's returnFocus falls through to a module-global stack and restores some
unrelated element from an earlier popover — blurring the field into its
own commit-and-close, from the second popover of a session onward. The
context menu now owns the restore: back to the row, but only if the row
is still there and nothing else has claimed focus.

Also:
- Backspace under the cheat sheet stopped Plex playback and dropped to
  the grid; `back` now defers to any layer above, like `escape` beside it.
- A move invalidated only the source list, so the target kept serving
  pre-move contents for 30s while the rail already counted N+1.
- Every move error a user can reach is a 404, which `req` leaves to the
  caller — so the row snapped back in silence and the shipped moveErrors
  strings were unreachable.
- swallowClick armed on long-press but was disarmed only by the click it
  was armed for; any press that produced no click ate the next tap on the
  whole list.
- The context menu stayed parked over whatever row scrolled under it.
- overflow-clip on the chip lanes ate the focus ring's top and bottom.
- "Why is this off" rode on disabled rows, which show no tooltip and take
  no focus: a new `inert` item keeps the reason readable.
- Shift+F10 was advertised app-wide but wired only on Playlists; it has
  its own scope now, and useContextMenu matches through the shared parser
  instead of its own literals.
- Mod+K could not close the palette, `h` machine-gunned on auto-repeat,
  and both were bound above the branch that mounts their overlays.
- Palette options were in the tab order under aria-activedescendant, and
  a scroll-synthesised mousemove stole the keyboard selection.
- The OSD live region was created together with its own text.
- Ending a rename stranded focus on <body>.
- The Button variants' hover halves are `enabled:` — the one migrated
  site that had guarded its own lost the guard on the way in.
- HU builtinLocked named the list "Watch later" in a Hungarian sentence.

Tests: the chip-lane contract counted per FILE, so a second hand-rolled
lane in an already-compliant file was invisible; the closeThenNavigate
ordering test only passed on a popstate left behind by its neighbours and
failed alone, so it moved to its own file.

frontend/src/components/Playlists.tsx

@@ -39,7 +39,7 @@ import {
   X,
   Youtube,
 } from "lucide-react";
-import { api, type Playlist, type Video } from "../lib/api";
+import { api, HttpError, type Playlist, type Video } from "../lib/api";
 import { notify } from "../lib/notifications";
 import { notifyYouTubeActionError } from "../lib/youtubeErrors";
 import { playlistName } from "../lib/playlistName";
@@ -516,10 +516,24 @@ export default function Playlists() {
         level: "success",
         message: t("playlists.movedToast", { title: video.title, name: plName(target) }),
       });
-    } catch {
-      // api.req already surfaced the reason; the refetch below puts the row back.
+    } catch (e) {
+      // NOT a silent revert. `req` deliberately leaves 401/403/404 to the caller as control flow, and
+      // every move failure a user can actually reach is a 404 (the 400 `same_playlist` case is already
+      // impossible — the submenu never offers the current list). So the row used to snap back with no
+      // explanation and the shipped moveErrors strings were unreachable (E10 review round 1).
+      // `req` already localized the structured `{code, reason}` into HttpError.detail — this is the
+      // consumer it was always missing.
+      notify({
+        level: "error",
+        message: e instanceof HttpError && e.detail ? e.detail : t("playlists.moveFailed"),
+      });
     }
-    refreshAll();
+    // BOTH sides changed, and so did this video's membership. `qk.playlist(selectedId)` is an exact
+    // key, so it cannot cover the target — invalidate the whole `["playlist"]` prefix, exactly as
+    // AddToPlaylist does for the same reason.
+    qc.invalidateQueries({ queryKey: qk.playlists() });
+    qc.invalidateQueries({ queryKey: qk.playlist() });
+    qc.invalidateQueries({ queryKey: qk.playlistMembership(video.id) });
   }
 
   // Keyboard/menu reordering, for the same stored order the drag handle writes — so it goes through
@@ -627,7 +641,11 @@ export default function Playlists() {
                     label: t("playlists.moveTo"),
                     icon: <FolderInput className="w-4 h-4" />,
                     separatorBefore: true,
-                    disabled: true,
+                    // `inert`, not `disabled`: a natively disabled <button> fires no pointer events
+                    // (so the title never shows) and roving focus skips it (so the keyboard never
+                    // reaches it) — the reason reached nobody, which is the post-mortem this file
+                    // already carries for the drag handle (E10 review round 1).
+                    inert: true,
                     title: t("playlists.moveNoTargets"),
                     onSelect: () => {},
                   },
@@ -645,7 +663,7 @@ export default function Playlists() {
                 separatorBefore: i === 0,
                 // Same gate as the drag handle, and it explains itself the same way instead of
                 // silently doing nothing.
-                disabled: !storedOrderEditable,
+                inert: !storedOrderEditable,
                 title: storedOrderEditable ? undefined : dragHint,
                 onSelect: () => moveInOrder(ctxRow, to),
               })),