Pass OAuth2 scopes to connector at initiate time

Add an InitiateOptions struct to the Connector interface so each
caller can declare the scopes it needs instead of having them baked
into the connector at registration. The HTTP handler reads repeated
?scope= query parameters from /connectors/initiate and forwards them.

Also restore GOOGLE_WORKSPACE and LINEAR provider definitions which
were silently dropped from the bootstrap config refactor.

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

pkg/connector/oauth2_test.go

@@ -27,6 +27,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"go.probo.inc/probo/pkg/gid"
 )
 
 func TestBuildTokenRequest_PostForm(t *testing.T) {
@@ -256,3 +257,57 @@ func TestClientCredentialsClient_ReusesValidToken(t *testing.T) {
 
 	assert.Equal(t, "existing-token", conn.AccessToken)
 }
+
+func TestInitiateWithState_Scopes(t *testing.T) {
+	t.Parallel()
+
+	t.Run("scopes are joined and set on auth URL", func(t *testing.T) {
+		t.Parallel()
+
+		c := &OAuth2Connector{
+			ClientID:     "id",
+			ClientSecret: "secret",
+			RedirectURI:  "https://example.com/cb",
+			AuthURL:      "https://provider.example.com/authorize",
+		}
+
+		orgID := gid.New(gid.NewTenantID(), 0)
+
+		u, err := c.InitiateWithState(
+			context.Background(),
+			OAuth2State{OrganizationID: orgID.String(), Provider: "TEST"},
+			InitiateOptions{Scopes: []string{"read:user", "write:user"}},
+			nil,
+		)
+		require.NoError(t, err)
+
+		parsed, err := url.Parse(u)
+		require.NoError(t, err)
+		assert.Equal(t, "read:user write:user", parsed.Query().Get("scope"))
+	})
+
+	t.Run("empty scopes omits scope parameter", func(t *testing.T) {
+		t.Parallel()
+
+		c := &OAuth2Connector{
+			ClientID:     "id",
+			ClientSecret: "secret",
+			RedirectURI:  "https://example.com/cb",
+			AuthURL:      "https://provider.example.com/authorize",
+		}
+
+		orgID := gid.New(gid.NewTenantID(), 0)
+
+		u, err := c.InitiateWithState(
+			context.Background(),
+			OAuth2State{OrganizationID: orgID.String(), Provider: "TEST"},
+			InitiateOptions{},
+			nil,
+		)
+		require.NoError(t, err)
+
+		parsed, err := url.Parse(u)
+		require.NoError(t, err)
+		assert.False(t, parsed.Query().Has("scope"), "scope param should be absent when no scopes provided")
+	})
+}