Refactor insights handling and error encoding in presentation layer

- Updated insights analyzer tests to use Utc for date handling.
- Added timezone support for insights retrieval, allowing insights to be bucketed by the user's local time.
- Introduced `encode_domain_error` for better error handling in API responses.
- Modified various handlers to utilize the new error encoding function.
- Enhanced insights API to reject unknown time zones and return appropriate errors.
- Updated frontend components to handle insights data with timezone awareness.
- Improved localization for insights sample counts.

crates/worker/src/main.rs

@@ -307,10 +307,24 @@ async fn main() -> anyhow::Result<()> {
 }
 
 fn init_tracing() {
-    let filter = std::env::var("RUST_LOG")
-        .unwrap_or_else(|_| "worker=info,application=info,k_ap=info".to_string());
     tracing_subscriber::registry()
-        .with(tracing_subscriber::EnvFilter::new(filter))
+        .with(log_filter("worker=info,application=info,k_ap=info"))
         .with(tracing_subscriber::fmt::layer())
         .init();
 }
+
+/// `RUST_LOG` names the crates to trace in detail; anything it doesn't name
+/// still reports warnings and errors. Without a baseline, a filter like
+/// `presentation=debug` silently drops adapter errors (e.g. the sqlx detail
+/// behind "Database operation failed").
+fn log_filter(default: &str) -> tracing_subscriber::EnvFilter {
+    let directives = std::env::var("RUST_LOG").unwrap_or_else(|_| default.to_string());
+    let has_baseline = directives
+        .split(',')
+        .any(|d| !d.trim().is_empty() && !d.contains('='));
+    if has_baseline {
+        tracing_subscriber::EnvFilter::new(directives)
+    } else {
+        tracing_subscriber::EnvFilter::new(format!("warn,{directives}"))
+    }
+}