refactor(server): finish the Org to Instance rename

Private identifiers plan 0b's naming map missed, plus the OrgOIDC model type.
No wire format, database field or route changes.

server/internal/api/instance.go

@@ -145,7 +145,7 @@ func putInstanceOIDC(c *gin.Context) {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
 	}
-	if err := services.SaveOrgOIDC(auth.InstanceID(c), body.Issuer, body.ClientID, body.ClientSecret, body.Enabled); err != nil {
+	if err := services.SaveInstanceOIDC(auth.InstanceID(c), body.Issuer, body.ClientID, body.ClientSecret, body.Enabled); err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
 	}