feat(web): series, season and episode removal

Series detail exposes DELETE /api/series/{id} through the movie
removePanel, generalised over endpoints and file rollup instead of
copied. Season headers and on-disk episode rows get the settings
armed-delete control wired to #174's file endpoints, worded for what
they do: files go, wanted clears, the row stays listed.

Closes #175

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/src/series.ts

@@ -149,6 +149,68 @@ export async function setEpisodeWanted(episodeId: number, wanted: boolean): Prom
   }
 }
 
+/* ---- removal (issues 174 + 175) ---------------------------------------- */
+
+/**
+ * The §7.4 title folder these episode files share. Season subfolders differ
+ * between files, so the shared folder is the one carrying the `[tmdbid-…]`
+ * tag every §7.4 title folder name has. `null` when the files disagree,
+ * which the panel then says instead of naming one folder falsely.
+ */
+export function seriesFolder(files: { path: string }[]): string | null {
+  const folders = new Set<string>();
+  for (const file of files) {
+    const parts = file.path.split("/");
+    const titleAt = parts.findIndex((part) => part.includes("[tmdbid-"));
+    const folder =
+      titleAt > 0
+        ? parts.slice(0, titleAt + 1).join("/")
+        : file.path.slice(0, file.path.lastIndexOf("/"));
+    if (folder === "") {
+      return null;
+    }
+    folders.add(folder);
+  }
+  if (folders.size !== 1) {
+    return null;
+  }
+  return [...folders][0] ?? null;
+}
+
+/**
+ * Remove the series from the library. The row and its §7.4 title folder go.
+ * Torrents keep seeding — the reaper owns that lifecycle (§7.3).
+ */
+export function removeSeries(seriesId: number): Promise<ActionOutcome> {
+  return del(`/api/series/${seriesId}`);
+}
+
+/**
+ * #174: the season's files go and its episodes stop being wanted. The season
+ * stays listed — TMDB owns that metadata and the next refresh would recreate
+ * it anyway.
+ */
+export function removeSeasonFiles(seriesId: number, seasonNumber: number): Promise<ActionOutcome> {
+  return del(`/api/series/${seriesId}/seasons/${seasonNumber}/files`);
+}
+
+/** #174, one episode: the file goes and the episode stops being wanted. */
+export function removeEpisodeFiles(episodeId: number): Promise<ActionOutcome> {
+  return del(`/api/episodes/${episodeId}/files`);
+}
+
+async function del(url: string): Promise<ActionOutcome> {
+  try {
+    const response = await fetch(url, { method: "DELETE" });
+    if (!response.ok) {
+      return { kind: "error", detail: await errorDetail(response) };
+    }
+    return { kind: "done" };
+  } catch {
+    return { kind: "error", detail: "daemon unreachable" };
+  }
+}
+
 /* ---- manual triggers and decks ---------------------------------------- */
 
 /** §6.2 manual search, one targeted sweep, for a season or an episode. */