Add SendGrid access review driver

Implement a SendGrid access-review driver that fetches teammates
from the SendGrid API and maps them into AccountRecord values.

Register SendGrid as a connector provider, expose it through the
connector provider enum, and add a migration that extends the
connector_provider type with SENDGRID.

Cover the new driver with a VCR-backed fixture test and helper
tests for role and response-shape handling to keep parsing robust.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/connector/provider/sendgrid.go

@@ -0,0 +1,36 @@
+// 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 provider
+
+import (
+	"context"
+	"net/http"
+
+	"go.gearno.de/kit/log"
+	"go.probo.inc/probo/pkg/accessreview/drivers"
+	"go.probo.inc/probo/pkg/coredata"
+)
+
+func sendgridRegistration() *Registration {
+	return &Registration{
+		Provider:       coredata.ConnectorProviderSendGrid,
+		DisplayName:    "SendGrid",
+		ProbeURL:       "https://api.sendgrid.com/v3/teammates?limit=1&offset=0",
+		SupportsAPIKey: true,
+		NewDriver: func(_ context.Context, c *http.Client, _ *coredata.Connector, _ *log.Logger) (drivers.Driver, error) {
+			return drivers.NewSendGridDriver(c), nil
+		},
+	}
+}