fix(downloads): a download larger than the space left says so, not "processing failed"

yt-dlp refuses a file announced over `max_filesize` by logging one line and returning with no file
(measured, and pinned in test_formats against a local server): the worker found no output and
failed the job as `postprocess`. `formats.watching_size_cap` now sees that line through our yt-dlp
logger, and the download (and, should it ever happen, a YouTube clip's range fetch) fails as the
owner's refusal with DOWNLOAD_TOO_BIG_MESSAGE, classified `quota_exceeded`. The download's quota
copy says it does not fit in what is left — true at a full cap too — instead of "Storage full".
A pre-existing type error the change touched is fixed (baseline down by one).

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

@@ -307,8 +307,8 @@
           "body": "Something went wrong with this download. The technical details below may help."
         },
         "quota_exceeded": {
-          "short": "Storage full",
-          "body": "This download was stopped because your storage quota is already used up. Delete something from your library, then try again."
+          "short": "Not enough storage",
+          "body": "This download doesn't fit in the storage you have left. Delete something from your library, then try again."
         }
       },
       "catalog": {

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

@@ -307,8 +307,8 @@
           "body": "Valami hiba történt ennél a letöltésnél. Az alábbi technikai részletek segíthetnek."
         },
         "quota_exceeded": {
-          "short": "Betelt a tárhely",
-          "body": "Ez a letöltés leállt, mert a tárhelykereted már elfogyott. Törölj valamit a könyvtáradból, aztán próbáld újra."
+          "short": "Nincs elég tárhely",
+          "body": "Ez a letöltés nem fér bele a megmaradt tárhelyedbe. Törölj valamit a könyvtáradból, aztán próbáld újra."
         }
       },
       "catalog": {