ui: loading states, player failure overlay + retry, toasts, back nav, full history page with delete

Bundle 1-4+7 from PLAN.md: skeleton loaders, player Loading/Buffering/fatal overlay with Retry, action toasts, back-to-home crumb + logo fix, ?history full-history view with per-entry delete (GET /api/history?all=1, DELETE /api/history). 14/14 tests green.

server/app.py

@@ -139,10 +139,23 @@ def _save_hist(user: str, entries):
 @app.get("/api/history")
 def api_history(request: Request):
     # no-store: this JSON mutates while a tab is open (position saves);
-    # a stale copy has caused "poster gone" confusion before
-    return JSONResponse(
-        sorted(_load_hist(request.state.user), key=lambda e: e.get("t", 0), reverse=True)[:5],
-        headers={"Cache-Control": "no-store"})
+    # a stale copy has caused "poster gone" confusion before.
+    # ?all=1: full list for the /history page (no top-5 cap)
+    entries = sorted(_load_hist(request.state.user), key=lambda e: e.get("t", 0), reverse=True)
+    if request.query_params.get("all") != "1":
+        entries = entries[:5]
+    return JSONResponse(entries, headers={"Cache-Control": "no-store"})
+
+
+@app.delete("/api/history")
+def api_history_delete(request: Request, slug_id: str, ep_id: str):
+    # loose str() match on purpose: legacy rows store the same ep_id as int
+    # AND as string — one delete clears both ghost rows
+    entries = _load_hist(request.state.user)
+    keep = [e for e in entries
+            if not (str(e.get("slug_id")) == slug_id and str(e.get("ep_id")) == ep_id)]
+    _save_hist(request.state.user, keep)
+    return {"removed": len(entries) - len(keep)}
 
 
 @app.post("/api/history")