Reduce unnecessary API requests in preview mode

## Description

Preview mode is currently making many unnecessary API requests that are intended for the full Genesis Plaza experience but are not needed in preview mode. These include:
- Notification polling intervals
- Places data requests to populate maps (multiple requests per category)

While these features enhance discoverability in the full client, they create unnecessary overhead in preview mode where features like the minimap and sidebar aren't needed.

## Context

The current approach in Bevy loads places data from each category to avoid an empty-looking map (unlike Unity's approach), and requests load lazily in the background during startup. However, preview mode doesn't need this functionality.

## Proposed Solution

Implement a reduced system scene configuration for preview mode using feature flags or similar mechanisms. This would:
- Remove minimap, sidebar, and other UI elements not needed for preview
- Disable unnecessary API polling (notifications, places data)
- Potentially add preview-specific utilities if needed
- Could be deployed separately if beneficial

This would not require a separate repository - feature flags or conditional loading would be sufficient.

## Related Discussion

From the team discussion:
- Pablo: "we can cache the requests for some time or to change the strategy, follow same than unity if necessary... although in my opinion bevy approach invites the discoverability of a rich world"
- The requests load lazily in background while starting up
- Consensus that a planned issue would be appropriate to manage this work

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Requested by rob via Slack