Claims remain pending indefinitely when QR is not scanned

[TrishaG189]

Problem

Currently, claims created through the camera flow remain in pending state indefinitely if the QR code is not scanned.

The Raspberry Pi camera app continuously polls for claim status (# Don't stop polling), which means:

• Unclaimed photos lead to infinite polling loops
• The claim database accumulates stale entries over time
• At large events, this can result in unnecessary load and degraded system behavior

Why this matters

In real-world usage, it is common for users to take photos but not complete the claim flow.

Without a lifecycle mechanism:

• Stale claims are never cleaned up
• Polling continues indefinitely
• System behavior becomes inefficient over time

Proposed Solution

• Add an expires_at field to claims
• Assign a TTL (default: 15 minutes) at claim creation
• Introduce a periodic cleanup job to mark expired claims

This ensures:

• Proper lifecycle management of claims
• Reduced unnecessary polling
• Cleaner and more predictable system behavior