clean(presentation): strip comments, kill dead code, extract constants

- remove all doc/inline comments
- delete unused ApiError variants (AuthRequired, NotImplemented) and helpers (internal, not_implemented)
- prefix lifetime-only AppState fields with _ to suppress dead_code warning
- extract magic numbers: TICK_INTERVAL_SECS, EXPIRY_THRESHOLD_HOURS, POLL_INTERVAL_SECS, EVENT_BUS_CAPACITY, DEFAULT_ACTIVITY_LIMIT, DEFAULT_SEARCH_LIMIT, etc
- replace inline serde_json::json! in sync_status with typed SyncStatusEntry
- fix mid-file import in schedule handler
- fix extractors: strip_prefix instead of magic offset 6
- fix unreachable pattern in wire_repositories with cfg guard
- use eq_ignore_ascii_case for content-type header check

crates/presentation/src/main.rs

@@ -1,5 +1,3 @@
-//! k-tv server entry point.
-
 use std::net::SocketAddr;
 
 use tower_http::cors::{Any, CorsLayer};
@@ -17,10 +15,8 @@ mod state;
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
-    // Load .env file if present
     let _ = dotenvy::dotenv();
 
-    // Initialize tracing
     tracing_subscriber::fmt()
         .with_env_filter(
             tracing_subscriber::EnvFilter::try_from_default_env()
@@ -28,7 +24,6 @@ async fn main() -> anyhow::Result<()> {
         )
         .init();
 
-    // Load config
     let config = infra_wiring::Config::from_env()
         .map_err(|e| anyhow::anyhow!("Config error: {}", e))?;
 
@@ -38,10 +33,8 @@ async fn main() -> anyhow::Result<()> {
 
     info!("Starting k-tv server on {}:{}", host, port);
 
-    // Build the application state (connects DB, creates adapters, spawns background tasks)
     let app_state = factory::build_app_state(config).await?;
 
-    // Build CORS layer
     let cors = if cors_origins.iter().any(|o| o == "*") {
         CorsLayer::new()
             .allow_origin(Any)
@@ -58,14 +51,12 @@ async fn main() -> anyhow::Result<()> {
             .allow_headers(Any)
     };
 
-    // Build the router
     let app = axum::Router::new()
         .nest("/api/v1", routes::api_v1_router())
         .layer(cors)
         .layer(TraceLayer::new_for_http())
         .with_state(app_state);
 
-    // Start serving
     let addr: SocketAddr = format!("{}:{}", host, port).parse()?;
     let listener = tokio::net::TcpListener::bind(addr).await?;
     info!("Listening on {}", addr);