Add five API-key access-review connectors

Add Mercury, Apollo.io, Deepgram, ClickHouse Cloud, and Langfuse as
access-review connectors. All are API-key, single-tenant providers
(Pattern 3): the key identifies one tenant, so there is no OAuth flow,
picker UI, or bootstrap/helm configuration.

- Mercury: Bearer token, GET /api/v1/users, cursor pagination.
- Apollo.io: x-api-key header, GET /api/v1/users/search (teammates).
- Deepgram: Token scheme; lists members across every project and
  dedupes by member_id, unioning per-project scopes.
- ClickHouse Cloud: HTTP Basic (keyId:keySecret); discovers the org
  via GET /v1/organizations, then lists its members.
- Langfuse: HTTP Basic (publicKey:secretKey); a base-URL setting
  selects the regional cloud host or a self-hosted instance.

Each adds the enum value, migration, GraphQL binding, provider
Registration, a driver with a cassette-driven test, and a brand logo.

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

pkg/connector/provider/apollo.go

@@ -0,0 +1,51 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.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 apolloRegistration() *Registration {
+	return &Registration{
+		Provider:       coredata.ConnectorProviderApollo,
+		DisplayName:    "Apollo.io",
+		SupportsAPIKey: true,
+		// Apollo's REST API authenticates with a master API key in the
+		// x-api-key header; it rejects Authorization: Bearer (and, since
+		// Sept 2024, query/body key params). APIKeyHeader makes the
+		// APIKeyConnection send x-api-key instead of Bearer. There is no
+		// OAuth2 flow needed: the customer supplies a master key, which is
+		// bound to one Apollo account, so there is nothing to pick
+		// (Pattern 3): no settings struct, no picker.
+		APIKeyHeader: "x-api-key",
+		// ProbeURL lets the connection-status check confirm the key with a
+		// lightweight GET; the transport attaches x-api-key, and a missing,
+		// dead, or non-master key returns 401/403.
+		ProbeURL: "https://api.apollo.io/api/v1/users/search?page=1&per_page=1",
+		//
+		// No NewNameResolver: Apollo exposes no stable account-name
+		// endpoint reachable with the master key, so the source keeps its
+		// generic name.
+		NewDriver: func(_ context.Context, c *http.Client, _ *coredata.Connector, _ *log.Logger) (drivers.Driver, error) {
+			return drivers.NewApolloDriver(c), nil
+		},
+	}
+}