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/application/src/insights/get.rs

@@ -3,13 +3,20 @@
 //! thresholds. No caching, no snapshots — the same on-the-fly shape as the
 //! existing live stats.
 
+use chrono::TimeZone;
 use domain::{errors::DomainError, models::Insight, value_objects::UserId};
 
 use crate::insights::deps::GetInsightsDeps;
 
-pub async fn execute(deps: &GetInsightsDeps, user_id: UserId) -> Result<Vec<Insight>, DomainError> {
+pub async fn execute<Tz: TimeZone + Sync>(
+    deps: &GetInsightsDeps,
+    user_id: UserId,
+    tz: &Tz,
+) -> Result<Vec<Insight>, DomainError> {
     let rows = deps.insights.get_watch_rows(&user_id).await?;
-    Ok(domain::services::insights_analyzer::build_insights(&rows))
+    Ok(domain::services::insights_analyzer::build_insights(
+        &rows, tz,
+    ))
 }
 
 #[cfg(test)]

crates/application/src/insights/tests/get.rs

@@ -31,7 +31,9 @@ async fn returns_analyzer_output_for_the_user() {
         insights: InMemoryInsightsQuery::with_rows(user, rows),
     };
 
-    let insights = execute(&deps, UserId::from_uuid(user)).await.unwrap();
+    let insights = execute(&deps, UserId::from_uuid(user), &chrono::Utc)
+        .await
+        .unwrap();
     assert!(insights.iter().any(
         |i| matches!(i, domain::models::Insight::RatingLift { genre, .. } if genre == "Thriller")
     ));
@@ -49,7 +51,9 @@ async fn other_users_rows_are_not_seen() {
         insights: InMemoryInsightsQuery::with_rows(other, rows),
     };
 
-    let insights = execute(&deps, UserId::from_uuid(user)).await.unwrap();
+    let insights = execute(&deps, UserId::from_uuid(user), &chrono::Utc)
+        .await
+        .unwrap();
     assert!(insights.is_empty());
 }
 
@@ -60,7 +64,9 @@ async fn empty_diary_returns_empty_list() {
         insights: InMemoryInsightsQuery::new(),
     };
 
-    let insights = execute(&deps, UserId::from_uuid(user)).await.unwrap();
+    let insights = execute(&deps, UserId::from_uuid(user), &chrono::Utc)
+        .await
+        .unwrap();
     assert!(insights.is_empty());
 }
 
@@ -83,7 +89,7 @@ async fn port_errors_propagate() {
         insights: Arc::new(Failing),
     };
 
-    let err = execute(&deps, UserId::from_uuid(Uuid::new_v4()))
+    let err = execute(&deps, UserId::from_uuid(Uuid::new_v4()), &chrono::Utc)
         .await
         .unwrap_err();
     assert!(matches!(