[Feat] Add Teams destination for config error alerts

[roomote-roomote]

Opened on behalf of Daniel Riccio. Follow up by mentioning @roomote-roomote, in the web UI, or in Discord.

What changed

Added an explicit Microsoft Teams destination for Alert on Config Errors. Administrators can select an installed Teams conversation in Automations Settings, and configuration-error alerts are delivered to that saved destination.

Why this change was made

Teams alert delivery must be predictable. Selecting a saved destination avoids routing to whichever Teams conversation happened to be active most recently.

Impact

Teams deployments can use an existing operational channel or group chat for config-error alerts without creating a separate channel. Slack and Discord delivery remain unchanged.

[roomote-roomote]

1 issue outstanding. See task

• apps/web/src/trpc/commands/automations/settings-update.ts:539-541 Older clients omit the newly optional platformIssueTeamsChannel field. When they save Alert on Config Errors after a Teams destination has been selected, this treats omission as null, removes the Teams target, and disables alerts instead of preserving the existing destination. Match the optional Discord field's preserve-on-omission behavior, while still clearing Teams when a client explicitly selects Slack or Discord.

_{Reviewed fc9f400}