feat: add per-hoster provider routing (Hoster-Zuordnung)

- New settings field hosterRouting maps file hosters to specific debrid providers
- 27 known hosters predefined (Rapidgator, Uploaded, Turbobit, Nitroflare, etc.)
- Custom hoster support via prompt dialog
- Routing takes priority over default provider chain
- Falls back to normal chain on error when autoProviderFallback is enabled
- Logs routing decisions: "Hoster-Zuordnung: rapidgator → Debrid-Link"
- Full UI section in settings with add/remove/change provider per hoster
- Storage validation and normalization for hosterRouting

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

src/renderer/styles.css

@@ -1305,6 +1305,69 @@ body,
   opacity: 1;
 }
 
+.hoster-routing-table {
+  display: flex;
+  flex-direction: column;
+  gap: 0;
+  border: 1px solid var(--border);
+  border-radius: 10px;
+  overflow: hidden;
+  margin-bottom: 10px;
+}
+
+.hoster-routing-header {
+  display: grid;
+  grid-template-columns: 1fr 1fr 40px;
+  gap: 10px;
+  padding: 8px 12px;
+  background: color-mix(in srgb, var(--card) 80%, var(--surface));
+  font-size: 0.78rem;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.04em;
+  color: var(--muted);
+  border-bottom: 1px solid var(--border);
+}
+
+.hoster-routing-row {
+  display: grid;
+  grid-template-columns: 1fr 1fr 40px;
+  gap: 10px;
+  padding: 6px 12px;
+  align-items: center;
+  border-bottom: 1px solid color-mix(in srgb, var(--border) 40%, transparent);
+}
+
+.hoster-routing-row:last-child {
+  border-bottom: none;
+}
+
+.hoster-routing-label {
+  font-weight: 500;
+  font-size: 0.88rem;
+}
+
+.hoster-routing-row select {
+  padding: 4px 8px;
+  font-size: 0.84rem;
+}
+
+.hoster-routing-row .btn-sm {
+  padding: 2px 8px;
+  font-size: 0.9rem;
+  min-width: 28px;
+  line-height: 1.4;
+  border-radius: 6px;
+}
+
+.hoster-routing-add {
+  margin-top: 8px;
+}
+
+.hoster-routing-add select {
+  max-width: 260px;
+}
+
 .account-modal {
   width: min(960px, calc(100vw - 36px));
   max-height: calc(100vh - 36px);