fix(DashboardLayout): render NavigationItem.action as ListItem secondfix(DashboardLayout): render NavigationItem.action as ListItem's secondaryAction

[forurmah]

Fixes #4747

When a NavigationItem has an action (e.g. a button rendered in the expanded sidebar), it was rendered inside the clickable NavigationListItemButton, so pointer events on the action also triggered the parent nav item's click handler.

This moves item.action out of the button and passes it via ListItem's built-in secondaryAction prop instead, following MUI's standard pattern for this composition — the action now renders as a sibling of the button rather than a nested clickable element, so clicks no longer propagate.

[mui-bot]

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[forurmah]

Looks like the CI failures are unrelated to this change — the CircleCI logs show:
"Orb codecov/codecov@5.4.3 not loaded. To use this orb, your organization must enable the 'Allow uncertified public orbs' feature in Org Settings > Security."
This seems to be an org-level CircleCI config issue rather than something caused by this PR.