fix(history): recherche et filtres fonctionnels sur les 3 onglets

- distinctUntilChanged() sur Subject<void> avalait toutes les frappes
  apres la premiere : barre de recherche morte sur les 3 onglets.
- Filtre provider recherches : ids courts stockes (yt, dm) vs filtre
  long (youtube) -> zero resultat. Match court+long cote serveur.
- LIKE echappes (%, _, \\) sur q des 3 onglets.
- Watch/transcripts : provider normalise (court+long), lang
  insensible a la casse avec prefixe (fr -> fr, fr-ca).
- Ecriture watch canonique (nom long). Test test:history.

docs/user-management.md

@@ -199,15 +199,17 @@ Responses typically include: `{ user: {id, username, email}, accessToken, sessio
 - PATCH `/user/preferences` → { language?, defaultProvider?, theme?, videoQuality?, region? }
 
 ### History
-- GET `/user/history/search?limit=&before=`
+- GET `/user/history/search?limit=&before=&q=&provider=` (provider court `yt` ou long `youtube`, LIKE échappés)
 - POST `/user/history/search` → { query, filters? }
 - DELETE `/user/history/search/:id` | `/user/history/search?all=1`
 
-- GET `/user/history/watch?limit=&before=`
+- GET `/user/history/watch?limit=&before=&q=&provider=` (titre/provider/video_id, LIKE échappés, provider normalisé)
 - POST `/user/history/watch` → { provider, videoId, title?, watchedAt, progressSeconds?, durationSeconds? }
 - PATCH `/user/history/watch/:id` → { progressSeconds?, lastPositionSeconds? }
 - DELETE `/user/history/watch/:id` | `/user/history/watch?all=1`
 
+- GET `/user/history/transcripts?limit=&before=&q=&provider=&lang=` (`lang=fr` matche `fr` + `fr-ca`, insensible à la casse ; `q` cherche aussi dans le texte conservé)
+
 ### Subscriptions & Categories
 - GET `/user/subscriptions?category=&provider=`
 - POST `/user/subscriptions` → { provider, channelId, channelName?, notify? }