fix(feed): a filter on a deleted tag matches nothing and its chip says so

A saved view or the stored filter outlives its tag. feedquery dropped the unknown id, so the
view showed the whole feed under its old name. The id now lands in a MISSING_TAG_CATEGORY that
filters to nothing in the SQL and in feed_summary's mirror alike; the feed chip reads "Deleted
tag" (a placeholder while the tag list loads, the id if it failed). Channels' persisted tag
filter gets the same chip, first in the row so the +N overflow cannot fold it away.

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

@@ -57,6 +57,7 @@
     "createFailed": "Couldn't create the tag",
     "updateFailed": "Couldn't update the tag",
     "noTag": "No tag",
+    "deleted": "Deleted tag",
     "moreCount_one": "{{count}} more tag",
     "moreCount_other": "{{count}} more tags",
     "suggestedHint": "Suggested from your tagging pattern ({{pct}}% match) — click to add",

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

@@ -4,6 +4,7 @@
     "remove": "Remove filter: {{name}}",
     "contentNone": "No content types",
     "untagged": "Untagged",
+    "deletedTag": "Deleted tag",
     "count_one": "{{count}} filter",
     "count_other": "{{count}} filters",
     "moreCount_one": "{{count}} more filter",

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

@@ -57,6 +57,7 @@
     "createFailed": "Nem sikerült létrehozni a címkét",
     "updateFailed": "Nem sikerült frissíteni a címkét",
     "noTag": "Nincs címke",
+    "deleted": "Törölt címke",
     "moreCount_one": "még {{count}} címke",
     "moreCount_other": "még {{count}} címke",
     "suggestedHint": "A címkézési mintád alapján javasolt ({{pct}}% egyezés) — kattints a hozzáadáshoz",

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

@@ -4,6 +4,7 @@
     "remove": "Szűrő eltávolítása: {{name}}",
     "contentNone": "Nincs tartalomtípus",
     "untagged": "Címkézetlen",
+    "deletedTag": "Törölt címke",
     "count_one": "{{count}} szűrő",
     "count_other": "{{count}} szűrő",
     "moreCount_one": "még {{count}} szűrő",