Generate and store single-use auth token for pairing

We need to record whether the token has been used. The token must be replaced with a fresh token if the user restarts the pairing process.

changed milestone to %Mailbox: Database

added Sponsor 6 T: task labels

mentioned in issue #48 (closed)

marked this issue as related to #48 (closed)

mentioned in issue #50 (closed)

marked this issue as related to #50 (closed)

added Mailbox label

We could probably store this in Settings in the DB in order to avoid having to define a custom table just for that.

assigned to @grote

added S: in progress label

mentioned in merge request !30 (merged)

mentioned in commit 97b828ab

closed with merge request !30 (merged)

Needs weight.

added R: fixed label and removed S: in progress label

added Weight: 1 label

added Mailbox app label