Mejoras de estabilidad de stream IPTV y nuevo registro de fallos

- restream.py: eliminar -reconnect_streamed de ffmpeg para evitar rebobinados
  al reconectar (el proveedor re-enviaba desde keyframe anterior causando PTS
  backward). El loop de Python gestiona las reconexiones con conexión fresca.
- restream.py: eliminar _drain_queue del loop de reconexión para que el buffer
  de la cola cubra el tiempo de reconexión sin pantalla negra en el player.
- restream.py: añadir buffer_server_bytes/secs/capacity a stats() y método
  _log_stream_event() para persistir eventos de caída y recuperación en BD.
- models/stream_event.py: nuevo modelo StreamEvent para registro de fallos.
- database.py: registrar StreamEvent en init_db.
- api/admin/logs.py: nuevos endpoints GET/DELETE /logs/events.
- Dashboard.tsx: mostrar reserva de buffer del servidor (capacidad + estado).
- Logs.tsx: añadir pestaña "Fallos de stream" con tabla de eventos persistidos.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/core/jellyfin_client.py

@@ -0,0 +1,120 @@
+"""Async Jellyfin API client — discovery, libraries, items, streaming."""
+import logging
+
+import aiohttp
+
+logger = logging.getLogger(__name__)
+
+_SHORT = aiohttp.ClientTimeout(total=10)
+_MEDIUM = aiohttp.ClientTimeout(total=30)
+_LONG = aiohttp.ClientTimeout(total=60)
+
+
+class JellyfinClient:
+    def __init__(self, url: str, api_key: str):
+        self.url = url.rstrip("/")
+        self.api_key = api_key
+
+    @property
+    def _headers(self) -> dict:
+        return {"X-Emby-Token": self.api_key, "Accept": "application/json"}
+
+    # ------------------------------------------------------------------
+    # Discovery
+    # ------------------------------------------------------------------
+
+    async def test_connection(self) -> dict:
+        async with aiohttp.ClientSession() as s:
+            async with s.get(
+                f"{self.url}/System/Info/Public", timeout=_SHORT
+            ) as r:
+                r.raise_for_status()
+                return await r.json()
+
+    async def get_libraries(self) -> list[dict]:
+        async with aiohttp.ClientSession() as s:
+            async with s.get(
+                f"{self.url}/Library/VirtualFolders",
+                headers=self._headers,
+                timeout=_SHORT,
+            ) as r:
+                r.raise_for_status()
+                data = await r.json()
+                return data if isinstance(data, list) else []
+
+    # ------------------------------------------------------------------
+    # Items (movies / series)
+    # ------------------------------------------------------------------
+
+    async def get_items(self, library_id: str, item_type: str) -> list[dict]:
+        """Fetch all items of a given type from one library (paginated)."""
+        all_items: list[dict] = []
+        start = 0
+        limit = 200
+        while True:
+            params = {
+                "ParentId": library_id,
+                "IncludeItemTypes": item_type,
+                "Recursive": "true",
+                "Fields": "Overview,Genres,OfficialRating,ProductionYear",
+                "Limit": str(limit),
+                "StartIndex": str(start),
+            }
+            async with aiohttp.ClientSession() as s:
+                async with s.get(
+                    f"{self.url}/Items",
+                    params=params,
+                    headers=self._headers,
+                    timeout=_LONG,
+                ) as r:
+                    r.raise_for_status()
+                    data = await r.json()
+            batch = data.get("Items", [])
+            all_items.extend(batch)
+            total = data.get("TotalRecordCount", 0)
+            if len(all_items) >= total or not batch:
+                break
+            start += len(batch)
+        return all_items
+
+    # ------------------------------------------------------------------
+    # Series structure (seasons + episodes)
+    # ------------------------------------------------------------------
+
+    async def get_seasons(self, series_id: str) -> list[dict]:
+        async with aiohttp.ClientSession() as s:
+            async with s.get(
+                f"{self.url}/Shows/{series_id}/Seasons",
+                params={"Fields": "Overview"},
+                headers=self._headers,
+                timeout=_MEDIUM,
+            ) as r:
+                r.raise_for_status()
+                return (await r.json()).get("Items", [])
+
+    async def get_episodes(self, series_id: str, season_id: str) -> list[dict]:
+        async with aiohttp.ClientSession() as s:
+            async with s.get(
+                f"{self.url}/Shows/{series_id}/Episodes",
+                params={"SeasonId": season_id, "Fields": "Overview"},
+                headers=self._headers,
+                timeout=_MEDIUM,
+            ) as r:
+                r.raise_for_status()
+                return (await r.json()).get("Items", [])
+
+    # ------------------------------------------------------------------
+    # URL builders
+    # ------------------------------------------------------------------
+
+    def build_stream_url(self, item_id: str) -> str:
+        return (
+            f"{self.url}/Videos/{item_id}/stream"
+            f"?static=true&api_key={self.api_key}&Container=mkv"
+        )
+
+    def build_image_url(self, item_id: str, max_width: int = 400) -> str:
+        return (
+            f"{self.url}/Items/{item_id}/Images/Primary"
+            f"?api_key={self.api_key}&MaxWidth={max_width}"
+        )