feat(podcasts): hide played/downloaded toggle + episode text filter

Pocket Casts steal pulled forward from Phase 4 (§0 item 6): the episode
list gains a client-side 'Filter episodes…' box and a 'Hide
played/downloaded' toggle. Pure presentation — rows carry templ-rendered
data-* attributes (downloaded, listen-pct, search text); the filter
toggles DOM visibility with the 99.5% finishedThreshold. The toolbar
lives OUTSIDE #episode-list so its state survives the list's polling
swaps, and an htmx:afterSwap listener re-applies the active filter to
freshly swapped rows. No query change, no server round trip, no new JS
rendering surface (Alpine component method, CSP-safe).

web/src/podcasts.ts

@@ -22,6 +22,46 @@ Alpine.data("podcastsPage", () => ({
 // body declares (modal visibility) so CSP-bound Alpine stays happy.
 Alpine.data("podcastDetail", () => ({
   unsubOpen: false,
+  filterListenerInstalled: false,
+
+  // Episode-list filters (§0 item 6, 2026-10-30): hide played/
+  // downloaded rows and/or substring-filter titles+descriptions. Pure
+  // presentation — the DOM IS the data (rows carry data-* attributes
+  // rendered by templ); no query changes, no server round trip.
+  // finishedThreshold 99.5% matches the server's finished rule.
+  applyEpisodeFilter(): void {
+    const input = (this as any).$refs.episodeFilterInput as HTMLInputElement | undefined;
+    const box = (this as any).$refs.hideFinished as HTMLInputElement | undefined;
+    const emptyNote = (this as any).$refs.filterEmptyNote as HTMLElement | undefined;
+    const q = (input?.value ?? "").trim().toLowerCase();
+    const hideFinished = box?.checked ?? false;
+
+    let visible = 0;
+    let total = 0;
+    document.querySelectorAll<HTMLElement>("#episode-list [data-episode-row]").forEach((row) => {
+      total++;
+      const downloaded = row.dataset.downloaded === "true";
+      const pct = parseFloat(row.dataset.listenPct ?? "0");
+      const text = row.dataset.searchText ?? "";
+      const hide =
+        (hideFinished && (downloaded || pct >= 99.5)) ||
+        (q !== "" && !text.toLowerCase().includes(q));
+      row.classList.toggle("hidden", hide);
+      if (!hide) visible++;
+    });
+    if (emptyNote) emptyNote.classList.toggle("hidden", visible > 0 || total === 0);
+  },
+
+  // Re-apply after every htmx swap of the list (polling + action
+  // responses swap #episode-list wholesale; fresh rows must honor the
+  // active filter). Installed once per page.
+  initPodcastFilterPersistence(): void {
+    if (this.filterListenerInstalled) return;
+    this.filterListenerInstalled = true;
+    document.addEventListener("htmx:afterSwap", () => {
+      this.applyEpisodeFilter();
+    });
+  },
 }));
 
 // Add-feed form: surface the server's error text inline (the JSON error