fix: Implement pagination for device retrieval to prevent DoS

[LSUDOKO]

Description

This Pull Request addresses a Denial of Service (DoS) vulnerability in DeviceRegistry.sol where the getAllDevices function returned an unbounded array.

As the number of registered devices grows, returning the entire array could eventually exceed the Ethereum block gas limit, causing the function to revert. This would make it impossible for applications to retrieve device information.

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Changes Made

1. Implemented getDevicesPaginated

Added a new view function that allows callers to retrieve a subset of the registeredDevices array using cursor and count parameters.

2. Safe Indexing

Included validation checks to ensure:

• The cursor remains within valid bounds
• The returned array length is properly capped by the total number of registered devices

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Impact & Security Gains

• Prevents gas limit exhaustion when the dataset grows large.
• Ensures the system remains scalable as the number of registered cameras increases.
• Provides a reliable and efficient method for frontends and indexers to fetch device lists.

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fixes #14