feat(search): Library provenance filter (organic / all / search-only)

Replace the binary 'show search-discovered' toggle with a 3-way Source selector in the
Library toolbar, so users can also see ONLY search-discovered videos — not just hide or
mix them. Backend: feed param library_source = organic (default, hides via_search) | all
(both) | search (only via_search), applied in scope=all. Strings in HU/EN/DE.

frontend/src/components/Feed.tsx

@@ -417,20 +417,24 @@ export default function Feed({
         {filters.scope === "all" && (
           <>
             <span className="mx-1 h-5 w-px bg-border" aria-hidden="true" />
-            <button
-              onClick={() =>
-                setFilters({ ...filters, showSearchDiscovered: !filters.showSearchDiscovered })
-              }
-              aria-pressed={!!filters.showSearchDiscovered}
-              title={t("feed.searchDiscoveredTip")}
-              className={`text-xs px-3 py-1.5 rounded-full border transition ${
-                filters.showSearchDiscovered
-                  ? "bg-accent text-accent-fg border-accent"
-                  : "border-border text-muted hover:text-fg hover:border-accent"
-              }`}
-            >
-              {t("feed.searchDiscovered")}
-            </button>
+            <label className="inline-flex items-center gap-1.5 text-xs text-muted">
+              <span>{t("feed.source.label")}</span>
+              <select
+                value={filters.librarySource ?? "organic"}
+                onChange={(e) =>
+                  setFilters({
+                    ...filters,
+                    librarySource: e.target.value as FeedFilters["librarySource"],
+                  })
+                }
+                title={t("feed.source.tip")}
+                className="bg-card border border-border rounded-lg px-2 py-1 text-xs outline-none focus:border-accent"
+              >
+                <option value="organic">{t("feed.source.organic")}</option>
+                <option value="all">{t("feed.source.all")}</option>
+                <option value="search">{t("feed.source.only")}</option>
+              </select>
+            </label>
           </>
         )}
       </div>

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

@@ -30,8 +30,13 @@
   "markedWatchedNamed": "Als angesehen markiert: „{{title}}”",
   "markedWatched": "Als angesehen markiert",
   "unwatch": "Nicht mehr als angesehen",
-  "searchDiscovered": "Über Suche gefunden",
-  "searchDiscoveredTip": "Auch Videos anzeigen, die nur über eine Live-YouTube-Suche in die Bibliothek kamen.",
+  "source": {
+    "label": "Quelle",
+    "tip": "Bibliothek danach filtern, wie Videos hierher kamen: nur organischer Katalog, mit Suchergebnissen, oder nur über Live-YouTube-Suche gefundene Videos.",
+    "organic": "Ohne Suchergebnisse",
+    "all": "Mit Suchergebnissen",
+    "only": "Nur Suchergebnisse"
+  },
   "yt": {
     "searchFor": "Auf YouTube suchen nach „{{query}}”",
     "resultsFor": "YouTube-Ergebnisse für „{{query}}”",

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

@@ -30,8 +30,13 @@
   "markedWatchedNamed": "Marked watched “{{title}}”",
   "markedWatched": "Marked watched",
   "unwatch": "Unwatch",
-  "searchDiscovered": "Search-discovered",
-  "searchDiscoveredTip": "Also show videos that entered the library only through a live YouTube search.",
+  "source": {
+    "label": "Source",
+    "tip": "Filter the Library by how videos got here: organic catalog only, plus search results, or only videos found via live YouTube search.",
+    "organic": "Hide search results",
+    "all": "Include search results",
+    "only": "Search results only"
+  },
   "yt": {
     "searchFor": "Search YouTube for “{{query}}”",
     "resultsFor": "YouTube results for “{{query}}”",

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

@@ -30,8 +30,13 @@
   "markedWatchedNamed": "Megnézettnek jelölve: „{{title}}”",
   "markedWatched": "Megnézettnek jelölve",
   "unwatch": "Megnézés visszavonása",
-  "searchDiscovered": "Keresésből talált",
-  "searchDiscoveredTip": "Mutasd azokat a videókat is, amelyek csak élő YouTube-keresésen át kerültek a könyvtárba.",
+  "source": {
+    "label": "Forrás",
+    "tip": "Szűrd a könyvtárat aszerint, hogyan kerültek be a videók: csak organikus katalógus, kereséssel együtt, vagy csak az élő YouTube-keresésből talált videók.",
+    "organic": "Keresés nélkül",
+    "all": "Kereséssel együtt",
+    "only": "Csak keresésből"
+  },
   "yt": {
     "searchFor": "Keresés a YouTube-on: „{{query}}”",
     "resultsFor": "YouTube találatok erre: „{{query}}”",

frontend/src/lib/api.ts

@@ -141,9 +141,9 @@ export interface FeedFilters {
   includeShorts: boolean;
   includeLive: boolean;
   show: string;
-  // Library (scope "all") only: when set, also show videos that entered the catalog via a
-  // live YouTube search. Default (falsy) hides that search-discovered "noise".
-  showSearchDiscovered?: boolean;
+  // Library (scope "all") only — provenance filter: "organic" (default) hides search-
+  // discovered videos, "all" mixes them in, "search" shows only them. Ignored for "my".
+  librarySource?: "organic" | "all" | "search";
   channelId?: string;
   channelName?: string;
   maxAgeDays?: number;
@@ -309,8 +309,8 @@ function filterParams(f: FeedFilters): URLSearchParams {
   if (f.dateTo) p.set("published_before", f.dateTo);
   if (f.minDuration != null) p.set("min_duration", String(f.minDuration));
   if (f.maxDuration != null) p.set("max_duration", String(f.maxDuration));
-  // Only relevant in Library scope; the backend ignores it for "my". Default = hide.
-  p.set("exclude_search_discovered", String(!f.showSearchDiscovered));
+  // Only relevant in Library scope; the backend ignores it for "my". Default = hide search.
+  p.set("library_source", f.librarySource ?? "organic");
   return p;
 }