style: run gofmt -s across all Go files

Fixes Go Report Card gofmt score from 52% to 100%.
Pure formatting changes — no logic modifications.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/config/config.go

@@ -37,9 +37,9 @@ type ServerConfig struct {
 
 // DatabaseConfig contains database connection configuration.
 type DatabaseConfig struct {
-	URL             string
-	MaxConnections  int
-	MigrationsPath  string
+	URL            string
+	MaxConnections int
+	MigrationsPath string
 }
 
 // SchedulerConfig contains scheduler timing configuration.
@@ -64,9 +64,9 @@ type AuthConfig struct {
 
 // RateLimitConfig contains rate limiting configuration.
 type RateLimitConfig struct {
-	Enabled    bool
-	RPS        float64 // Requests per second
-	BurstSize  int     // Maximum burst size
+	Enabled   bool
+	RPS       float64 // Requests per second
+	BurstSize int     // Maximum burst size
 }
 
 // CORSConfig contains CORS configuration.