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/langfuse.go

@@ -0,0 +1,89 @@
+// 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"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"go.gearno.de/kit/log"
+	"go.probo.inc/probo/pkg/accessreview/drivers"
+	"go.probo.inc/probo/pkg/coredata"
+)
+
+func langfuseRegistration() *Registration {
+	return &Registration{
+		Provider:       coredata.ConnectorProviderLangfuse,
+		DisplayName:    "Langfuse",
+		SupportsAPIKey: true,
+		// Langfuse's organization-scoped public API authenticates with HTTP
+		// Basic auth where the credential is publicKey:secretKey.
+		// APIKeyBasicAuthUserPass base64s the verbatim "publicKey:secretKey" the
+		// operator pastes (the empty-password APIKeyBasicAuth cannot carry
+		// the secret). The org API key is bound to one organization, so
+		// there is nothing to pick; only the regional/self-hosted base URL
+		// is per-tenant and is surfaced as an extra setting.
+		APIKeyBasicAuthUserPass: true,
+		ExtraSettings: []ExtraSetting{
+			{Key: "baseUrl", Label: "Base URL", Required: true},
+		},
+		// BuildProbeURL derives the probe endpoint from the per-connection
+		// base URL (the host is regional/self-hosted, so a static ProbeURL
+		// cannot express it); the transport attaches the Basic credential
+		// and a dead key returns 401/403.
+		BuildProbeURL: buildLangfuseProbeURL,
+		//
+		// No NewNameResolver: the memberships endpoint carries no
+		// organization name, so the source keeps its generic name.
+		NewDriver: func(_ context.Context, c *http.Client, conn *coredata.Connector, _ *log.Logger) (drivers.Driver, error) {
+			settings, err := coredata.ConnectorSettings[coredata.LangfuseConnectorSettings](conn)
+			if err != nil {
+				return nil, fmt.Errorf("cannot read langfuse connector settings: %w", err)
+			}
+
+			baseURL, err := normalizeLangfuseBaseURL(settings.BaseURL)
+			if err != nil {
+				return nil, fmt.Errorf("cannot create langfuse driver: %w", err)
+			}
+
+			return drivers.NewLangfuseDriver(c, baseURL), nil
+		},
+	}
+}
+
+func normalizeLangfuseBaseURL(raw string) (string, error) {
+	baseURL := strings.TrimSpace(raw)
+	if baseURL == "" {
+		return "", fmt.Errorf("base_url is required")
+	}
+
+	u, err := url.Parse(baseURL)
+	if err != nil {
+		return "", fmt.Errorf("base_url must be a valid URL: %w", err)
+	}
+
+	if (u.Scheme != "http" && u.Scheme != "https") || u.Host == "" {
+		return "", fmt.Errorf("base_url must be an http(s) URL")
+	}
+
+	u.Path = strings.TrimRight(u.Path, "/")
+	u.RawQuery = ""
+	u.Fragment = ""
+
+	return u.String(), nil
+}