feat: Sentinela v0.2.0 — Brazilian Financial Data API in Go

- 20 Go source files, single 16MB binary
- SQLite + FTS5 full-text search (pure Go, no CGO)
- BCB integration: Selic, CDI, IPCA, USD/BRL, EUR/BRL
- CVM integration: 2,524 companies from registry
- Fiber v2 REST API with 42 handlers
- Auto-seeds on first run (~5s for BCB + CVM)
- Token bucket rate limiter, optional API key auth
- Periodic sync scheduler (configurable)
- Graceful shutdown, structured logging (slog)
- All endpoints tested with real data

internal/api/middleware/apikey.go

@@ -0,0 +1,26 @@
+package middleware
+
+import (
+	"strings"
+
+	"github.com/gofiber/fiber/v2"
+)
+
+func NewAPIKeyAuth(apiKey string) fiber.Handler {
+	return func(c *fiber.Ctx) error {
+		if c.Path() == "/health" {
+			return c.Next()
+		}
+		key := c.Get("X-API-Key")
+		if key == "" {
+			auth := c.Get("Authorization")
+			if strings.HasPrefix(auth, "Bearer ") {
+				key = strings.TrimPrefix(auth, "Bearer ")
+			}
+		}
+		if key != apiKey {
+			return c.Status(401).JSON(fiber.Map{"error": "unauthorized"})
+		}
+		return c.Next()
+	}
+}