Add SDK version to cookie banner logs via middleware

Extract X-SDK-Version from request headers in a dedicated
middleware and store it in context. All ErrorCtx calls in the
cookie banner handler now include the sdk_version field.

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/server/api/cookiebanner/v1/sdk_version_middleware.go

@@ -0,0 +1,37 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package cookiebanner_v1
+
+import (
+	"context"
+	"net/http"
+)
+
+type sdkVersionCtxKey struct{}
+
+func newSDKVersionMiddleware() func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			sdkVersion := r.Header.Get("X-SDK-Version")
+			ctx := context.WithValue(r.Context(), sdkVersionCtxKey{}, sdkVersion)
+			next.ServeHTTP(w, r.WithContext(ctx))
+		})
+	}
+}
+
+func sdkVersionFromContext(ctx context.Context) string {
+	v, _ := ctx.Value(sdkVersionCtxKey{}).(string)
+	return v
+}