style: apply ruff format across backend + scripts (line-length 100)

Mechanical, whole-tree `ruff format` pass — no behaviour change. Recorded in
.git-blame-ignore-revs (next commit) so git blame skips it.

backend/app/plex/client.py

@@ -5,6 +5,7 @@ this client — Siftlode plays the LOCAL physical file (see app.plex.paths). Ple
 metadata, image proxying, and (P5) optional watch-state write-back. Requests JSON via the
 ``Accept: application/json`` header (Plex serves XML by default).
 """
+
 import logging
 from urllib.parse import quote
 
@@ -163,7 +164,9 @@ class PlexClient:
         self._write("PUT", f"/library/collections/{collection_rating_key}/items?uri={uri}")
 
     def remove_collection_item(self, collection_rating_key: str, item_rating_key: str) -> None:
-        self._write("DELETE", f"/library/collections/{collection_rating_key}/children/{item_rating_key}")
+        self._write(
+            "DELETE", f"/library/collections/{collection_rating_key}/children/{item_rating_key}"
+        )
 
     def rename_collection(self, section_key: str, collection_rating_key: str, title: str) -> None:
         self._write(
@@ -221,7 +224,11 @@ class PlexClient:
         return self._get("/accounts").get("Account", []) or []
 
     def watch_history(
-        self, min_viewed_at: int = 0, account_id: int | None = None, size: int = 500, max_pages: int = 40
+        self,
+        min_viewed_at: int = 0,
+        account_id: int | None = None,
+        size: int = 500,
+        max_pages: int = 40,
     ) -> list[dict]:
         """The watch-history rows (ratingKey / viewedAt / accountID / type) newer than `min_viewed_at`
         (epoch seconds), newest first — works without Plex Pass. The efficient "what changed since T"
@@ -255,7 +262,8 @@ class PlexClient:
         else:
             log.warning(
                 "watch_history hit the %d-page scan cap (since=%s); reconcile will catch the tail",
-                max_pages, min_viewed_at,
+                max_pages,
+                min_viewed_at,
             )
         return out