Add Better Stack access review connector

Better Stack exposes team members and pending invitations through its
Uptime API. Wire it as an access-review connector so a Better Stack
team can be reviewed in access-review campaigns.

Better Stack has no third-party OAuth app for listing members (its
OAuth is an end-user MCP sign-in), so the connector authenticates with
a Bearer API token plus the team name that scopes the team-members
listing. The driver paginates /api/v2/team-members, maps roles and
invitation records into account records, and the source name is
resolved from the configured team.

This wires the full surface: the provider enum and migration, the
connector settings, the registry registration with the team-name extra
setting, the GraphQL input and resolver marshaling, the frontend field
mapping and connector logo, and cassette-backed driver tests.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/server/api/console/v1/graphql/connector.graphql

@@ -28,6 +28,10 @@ enum ConnectorProvider
         @goEnum(value: "go.probo.inc/probo/pkg/coredata.ConnectorProviderSigNoz")
     SUPABASE
         @goEnum(value: "go.probo.inc/probo/pkg/coredata.ConnectorProviderSupabase")
+    BETTER_STACK
+        @goEnum(
+            value: "go.probo.inc/probo/pkg/coredata.ConnectorProviderBetterStack"
+        )
     GITHUB @goEnum(value: "go.probo.inc/probo/pkg/coredata.ConnectorProviderGitHub")
     INTERCOM
         @goEnum(value: "go.probo.inc/probo/pkg/coredata.ConnectorProviderIntercom")
@@ -141,6 +145,7 @@ input CreateAPIKeyConnectorInput {
     posthogRegion: String
     posthogInstanceUrl: String
     oktaDomain: String
+    betterStackTeamName: String
 }
 
 type CreateAPIKeyConnectorPayload {