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.

Cargo.toml

@@ -55,6 +55,7 @@ tracing-subscriber = { version = "0.3.23", features = ["env-filter"] }
 async-trait = "0.1.92"
 uuid = { version = "1.23.0", features = ["v4", "v5", "serde"] }
 chrono = { version = "0.4", features = ["serde"] }
+chrono-tz = "0.10"
 sqlx = { version = "0.8.6", features = [
     "runtime-tokio-rustls",
     "sqlite",