fix(player): related marks survive, Restart restarts, and refused pages offer nothing to click

- Every state and Watch-later write goes through features/video/videoWrites,
  which marks the never-refetched lists (related lists, live searches) once
  the server has it; a contract test holds it. The Notification Center's
  undo, the feed's reset and the Watch-later toggles skipped it before.
- Confirmed marks are also kept apart (qk.videoMarks) and laid over the
  related rows: a Show more page landing later rebuilt them from the pages
  it read when it started, and dropped a mark made meanwhile.
- Restart on a related video starts at 0 (the session's stored position
  won before), and on the one already playing it seeks.
- The watched toggle remembers each video's mark: Back showed the opened
  video's launch-time state after a related one was marked.
- The help sheet leaves out the player's keys while a layer above it has
  them waiting.
- After a refusal a retry cannot answer, neither Show more (related) nor
  Load more (live search) is offered; a failed live-search page keeps the
  results already read and says why under them.
- The related cap message counts requests, as the cap does.

frontend/src/i18n/locales/en/errors.json

@@ -189,7 +189,7 @@
     "recipient_required": "A recipient email is required",
     "registration_closed": "Registration is currently closed",
     "related_disabled": "Related videos are turned off on this instance.",
-    "related_daily_limit": "You've opened today's limit of related lists ({{limit}}). Try again tomorrow.",
+    "related_daily_limit": "You've reached today's related videos limit ({{limit}} requests — each list and each Show more counts one). Try again tomorrow.",
     "search_disabled": "Live YouTube search is turned off on this instance.",
     "search_daily_limit": "You've reached today's YouTube search limit ({{limit}}). Try again tomorrow.",
     "search_term_required": "Enter something to search for",

frontend/src/i18n/locales/hu/errors.json

@@ -189,7 +189,7 @@
     "recipient_required": "Adj meg egy címzett e-mail címet",
     "registration_closed": "A regisztráció jelenleg zárva van",
     "related_disabled": "A kapcsolódó videók ki vannak kapcsolva ezen a példányon.",
-    "related_daily_limit": "Elérted a mai kapcsolódó listák korlátját ({{limit}}). Próbáld holnap.",
+    "related_daily_limit": "Elérted a kapcsolódó videók mai korlátját ({{limit}} kérés — minden lista és minden „Mutass többet” egynek számít). Próbáld holnap.",
     "search_disabled": "Az élő YouTube-keresés ki van kapcsolva ezen a példányon.",
     "search_daily_limit": "Elérted a mai YouTube-keresési korlátot ({{limit}}). Próbáld holnap.",
     "search_term_required": "Írj be egy keresőkifejezést",