extract background tasks into worker binary

Move auto_scheduler, library_sync, broadcast_poller, webhook_consumer
from presentation/background/ into crates/worker/src/jobs/.
Presentation is now a pure HTTP server.

crates/presentation/Cargo.toml

@@ -45,8 +45,6 @@ thiserror = { workspace = true }
 async-trait = { workspace = true }
 anyhow = "1"
 dotenvy = "0.15"
-reqwest = { workspace = true }
-handlebars = "6"
 
 # Local-files streaming
 tokio-util = { version = "0.7", features = ["io"], optional = true }