presentation: HTTP server crate w/ handlers, routes, background tasks

Axum binary that wires all clean-arch crates together:
- AppState holds pre-built Deps structs (auth, channels, schedule, library, etc.)
- JWT extractors (CurrentUser, AdminUser, OptionalCurrentUser)
- Handlers delegate to application use cases, map to api-types DTOs
- Routes: auth, channels, schedule, library, admin, providers, config, iptv
- Background: auto-scheduler, broadcast poller, webhook consumer, library sync
- Factory builds everything from Config + DbPool
- SimpleProviderRegistry impl of IProviderRegistry trait
- NoopMediaProvider fallback

crates/presentation/src/handlers/config.rs

@@ -0,0 +1,56 @@
+//! System configuration handler.
+
+use axum::Json;
+use axum::extract::State;
+
+use api_types::{ConfigResponse, ProviderCapabilitiesResponse, ProviderInfo};
+
+use crate::errors::ApiError;
+use crate::state::AppState;
+
+/// GET /config — public system configuration
+pub async fn get_config(
+    State(state): State<AppState>,
+) -> Result<Json<ConfigResponse>, ApiError> {
+    let registry = &state.provider_registry;
+    let provider_ids = registry.provider_ids();
+    let primary_id = registry.primary_id().to_string();
+
+    let providers: Vec<ProviderInfo> = provider_ids
+        .iter()
+        .filter_map(|id| {
+            registry.capabilities(id).map(|caps| ProviderInfo {
+                id: id.clone(),
+                capabilities: ProviderCapabilitiesResponse::from(caps),
+            })
+        })
+        .collect();
+
+    let primary_caps = registry
+        .capabilities(&primary_id)
+        .map(ProviderCapabilitiesResponse::from)
+        .unwrap_or(ProviderCapabilitiesResponse {
+            collections: false,
+            series: false,
+            genres: false,
+            tags: false,
+            decade: false,
+            search: false,
+            streaming_protocol: "direct_file".to_string(),
+            rescan: false,
+            transcode: false,
+        });
+
+    let mut available_types = Vec::new();
+    #[cfg(feature = "jellyfin")]
+    available_types.push("jellyfin".to_string());
+    #[cfg(feature = "local-files")]
+    available_types.push("local_files".to_string());
+
+    Ok(Json(ConfigResponse {
+        allow_registration: state.config.allow_registration,
+        providers,
+        provider_capabilities: primary_caps,
+        available_provider_types: available_types,
+    }))
+}