📝 Add docstrings to feat/go-rewrite

Docstrings generation was requested by @blakeridgway.

* https://github.com/RideAware/admin-panel/pull/1#issuecomment-3528008426

The following files were modified:

* `cmd/admin-panel/main.go`
* `internal/config/config.go`
* `internal/database/database.go`
* `internal/email/email.go`
* `internal/handlers/auth.go`
* `internal/handlers/newsletter.go`
* `internal/handlers/subscribers.go`
* `internal/middleware/auth.go`

cmd/admin-panel/main.go

@@ -11,6 +11,10 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
+// main is the program entry point for the admin panel. It loads configuration,
+// initializes middleware and the database (closed on exit), configures a Gin
+// router with HTML templates and static assets, registers public and
+// authenticated routes, and starts the HTTP server on the configured port.
 func main() {
 	cfg := config.Load()
 	middleware.Init()