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/admin.rs

@@ -0,0 +1,66 @@
+//! Admin handlers.
+
+use axum::Json;
+use axum::extract::{Query, State};
+use serde::Deserialize;
+use std::collections::HashMap;
+
+use api_types::{ActivityEventResponse, SettingsResponse};
+use application::admin::{GetActivityLogQuery, GetSettingsQuery, UpdateSettingsCommand};
+
+use crate::errors::ApiError;
+use crate::extractors::AdminUser;
+use crate::state::AppState;
+
+/// GET /admin/settings
+pub async fn get_settings(
+    State(state): State<AppState>,
+    AdminUser(_user): AdminUser,
+) -> Result<Json<SettingsResponse>, ApiError> {
+    let pairs =
+        application::admin::get_settings::execute(&state.admin_deps, GetSettingsQuery).await?;
+    let settings: HashMap<String, String> = pairs.into_iter().collect();
+    Ok(Json(SettingsResponse { settings }))
+}
+
+/// PUT /admin/settings
+pub async fn update_settings(
+    State(state): State<AppState>,
+    AdminUser(_user): AdminUser,
+    Json(body): Json<HashMap<String, String>>,
+) -> Result<Json<SettingsResponse>, ApiError> {
+    let settings_vec: Vec<(String, String)> = body.into_iter().collect();
+    let cmd = UpdateSettingsCommand {
+        settings: settings_vec,
+    };
+    application::admin::update_settings::execute(&state.admin_deps, cmd).await?;
+
+    // Re-read after update
+    let pairs =
+        application::admin::get_settings::execute(&state.admin_deps, GetSettingsQuery).await?;
+    let settings: HashMap<String, String> = pairs.into_iter().collect();
+    Ok(Json(SettingsResponse { settings }))
+}
+
+#[derive(Debug, Deserialize)]
+pub struct ActivityLogParams {
+    pub limit: Option<u32>,
+}
+
+/// GET /admin/activity
+pub async fn get_activity_log(
+    State(state): State<AppState>,
+    AdminUser(_user): AdminUser,
+    Query(params): Query<ActivityLogParams>,
+) -> Result<Json<Vec<ActivityEventResponse>>, ApiError> {
+    let query = GetActivityLogQuery {
+        limit: params.limit.unwrap_or(50),
+    };
+    let events = application::admin::activity_log::execute(&state.admin_deps, query).await?;
+    Ok(Json(
+        events
+            .into_iter()
+            .map(ActivityEventResponse::from)
+            .collect(),
+    ))
+}