fix: resolve all linting and formatting issues

- Fix error return value checks (errcheck)
- Fix unused parameters by using underscore prefix
- Add missing package comments to all packages
- Fix context key type issue in middleware (use typed contextKey)
- Replace deprecated trace.NewNoopTracerProvider with noop.NewTracerProvider
- Fix embedded field selector in database client
- Remove trailing whitespace
- Remove revive linter (as requested) to avoid stuttering warnings for public API interfaces

All linting and formatting checks now pass.

internal/ent/schema/audit_log.go

@@ -1,3 +1,4 @@
+// Package schema defines the Ent schema for domain entities.
 package schema
 
 import (
@@ -46,4 +47,3 @@ func (AuditLog) Indexes() []ent.Index {
 		index.Fields("action"),
 	}
 }
-