Add a timestamp column to apps table

this field can be used in UI to see if more detailed app information
has to be fetched (since it calls the list apps REST API periodically)

migrations/schema.sql

@@ -71,8 +71,9 @@ CREATE TABLE IF NOT EXISTS apps(
     domain VARCHAR(128) NOT NULL,
     dnsRecordId VARCHAR(512), // tracks any id that we got back to track dns updates
     accessRestrictionJson TEXT, // { users: [ ], groups: [ ] }
-    creationTime TIMESTAMP(2) NOT NULL DEFAULT CURRENT_TIMESTAMP,
-    updateTime TIMESTAMP(2) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    creationTime TIMESTAMP(2) NOT NULL DEFAULT CURRENT_TIMESTAMP, // when the app was installed
+    updateTime TIMESTAMP(2) NOT NULL DEFAULT CURRENT_TIMESTAMP,   // when the last app update was done
+    ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, // when this db record was updated (useful for UI caching)
     memoryLimit BIGINT DEFAULT 0,
     xFrameOptions VARCHAR(512),
     sso BOOLEAN DEFAULT 1, // whether user chose to enable SSO