Add UI support for activity visibility/importance hints in workflow history

Is your feature request related to a problem? Please describe.

In workflows with many Activities, the Event History / compact view can become noisy when some Activities are operationally important for durability but low-value for day-to-day human debugging.

A common example is notification Activities: sending Slack messages, emails, webhooks, audit pings, or other side effects. These should still be recorded in Workflow History for correctness, replay, observability, and auditing, but they often distract from the main business flow when inspecting a Workflow Execution in the UI.

This is not a request to remove events from History or weaken Temporal's durability model. The underlying history should remain complete and immutable. The request is for a UI/view-level mechanism to collapse or hide lower-importance events by default.

Related but different: #2192 added/covered filtering around failed events. This request is about activity-level display hints / importance, ideally driven by metadata or naming conventions, so the UI can reduce operational noise without hiding failed events.

Describe the solution you'd like

Add support in Temporal UI for Activity display hints such as:

• normal / important: show by default
• collapsed: show as a compact single-line entry by default
• hidden / low-importance: hide from the default view, but reveal via a "show hidden/low-importance events" toggle

Possible implementation options:

1. UI-only filtering/collapse controls

   • Let users filter or collapse Activity events by Activity Type name, prefix, or category.
   • Example: collapse or hide Notification.* Activities by default.

2. Activity metadata / SDK-provided display hints

   • Allow SDKs to attach non-semantic display metadata to Activity scheduling, such as temporal.ui.visibility = collapsed or temporal.ui.importance = low.
   • The server would still persist the complete event history.
   • The UI would interpret this metadata only as a presentation hint.

3. Namespace/user saved preferences

   • Let users save Event History view preferences, such as hiding notification/audit activities unless there is a failure.

Describe alternatives you've considered

• Combine multiple notification Activities into one Notification.Dispatch Activity.
• Move notification logic into a Child Workflow so the parent workflow history is less noisy.
• Enqueue notifications to an external system and only record the enqueue Activity in Temporal.
• Encrypt payloads with a Payload Codec/Data Converter when the concern is sensitive data rather than UI noise.

These workarounds help, but they require modeling changes in application code. A UI-level visibility/importance mechanism would preserve the complete Event History while making the default debugging experience more human-friendly.

Additional context

The ideal behavior would be similar to log levels: low-level operational events are still available when needed, but the default view emphasizes the main business flow and failures.

Start by reviewing the Event History and compact view implementation, then compare the existing failed-event filtering from issue #2192. Clarify whether UI controls, activity metadata, or saved preferences are in scope; done means a defined presentation behavior that preserves complete history and keeps failed events discoverable.