Improve TLS handler with polling mechanism and configurable API URL

[Apoorv2712]

Summary

Improves the TLS handler with a polling mechanism for reliable scan results.

Changes

• Added configurable API URL via TLS_OBSERVATORY_API environment variable
• Implemented polling with retries (max 20 attempts, 2s interval) to wait for scan completion
• Added rescan=true parameter for fresh scans
• Added 408 timeout status with partial data when scan takes too long
• Improved error logging with response data

Why

The previous implementation immediately fetched results after triggering a scan, which could return incomplete data if the scan hadn't finished.

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