feat(automation): expose group title and allow setting secondary text

Surface {{groupNow.*}} template variables (title, note, colour, times,
custom fields) in the automation template autocomplete so events inside a
group can reference their group. The runtime store already carries
groupNow, so substitution and filters worked already; this makes it
discoverable.

Extend the message-secondary action with an optional text field so an
automation can set the secondary message content, not just its source.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LZYPZVdZLWowU7DyzGkWyy

packages/types/src/definitions/core/Automation.type.ts

@@ -111,9 +111,9 @@ export type OntimeAction =
       text?: string;
       visible?: boolean;
     }
-  // TODO: when setting a secondary source of type secondary we could specify a value to it
   | {
       type: 'ontime';
       action: OntimeMessageSecondary;
       secondarySource: SecondarySource;
+      text?: string;
     };