feat(channel): page details chaine multi-providers avec onglets et infinite scroll

- Strategy Pattern front: ChannelProviderInterface + 6 providers (yt/dm/tw/pt/od/ru) + factory (ids longs/courts)
- ChannelContentService: cache par onglet/tri/recherche (TTL 5min), pagination nextPage
- ChannelPage: header (banniere/avatar/subs/description ...plus), tabs dynamiques par capabilities, grilles videos/shorts 9:16/playlists/live, recherche debounced, tri recent/populaire, infinite scroll IntersectionObserver, skeletons/empty/error
- Backend: GET /api/channels/:provider/:id/content (videos/shorts/playlists/live) natif par provider

server/providers/rumble_fetch.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+"""
+Rumble Cloudflare bypass fetcher.
+
+Node's TLS fingerprint (OpenSSL) is blocked by Rumble's Cloudflare config, while
+curl_cffi's browser impersonation passes. This helper fetches a URL with
+curl_cffi impersonating a Chrome client and prints the raw HTML to stdout.
+
+Usage:  python3 rumble_fetch.py <url> [timeout_seconds]
+Exit codes: 0 = ok (stdout = html), 2 = HTTP error / challenge, 3 = curl_cffi missing.
+"""
+import sys
+
+URL = sys.argv[1] if len(sys.argv) > 1 else ""
+TIMEOUT = int(sys.argv[2]) if len(sys.argv) > 2 else 15
+
+try:
+    from curl_cffi import requests as curl_requests
+except ImportError:
+    sys.stderr.write("curl_cffi not installed\n")
+    sys.exit(3)
+
+if not URL:
+    sys.stderr.write("url required\n")
+    sys.exit(2)
+
+IMPERSONATE_CANDIDATES = ["chrome131", "chrome124", "chrome120", "safari18_0"]
+
+for target in IMPERSONATE_CANDIDATES:
+    try:
+        resp = curl_requests.get(
+            URL,
+            impersonate=target,
+            timeout=TIMEOUT,
+            allow_redirects=True,
+            headers={
+                "Accept-Language": "en-US,en;q=0.9",
+            },
+        )
+        body = resp.text or ""
+        if resp.status_code == 200 and "Just a moment" not in body[:4000]:
+            sys.stdout.write(body)
+            sys.exit(0)
+        # challenge or error: try next impersonation target
+        last_status = resp.status_code
+    except Exception as exc:  # noqa: BLE001
+        sys.stderr.write(f"{target}: {exc}\n")
+        last_status = 0
+
+sys.stderr.write(f"all impersonation targets failed (last={last_status})\n")
+sys.exit(2)