fix: implement safe dictionary lookups in HTML template to prevent KeyError

[Aarshpatel12]

Hi mentors! 👋

This PR addresses the PDF generation crash reported in Issue #38.

The Problem:

The render_report_html function was using strict dictionary lookups (e.g., data["basic_report"]). If the processor output omitted any of these keys, or changed the key names, it resulted in a fatal KeyError that crashed the endpoint.

The Solution:

• Safe Lookups: Replaced strict lookups with .get() methods and provided sensible fallback strings (e.g., "No basic report available.") so the template always renders gracefully.
• Format Flexibility: Added an isinstance check for asl_parameters so the template doesn't break whether it receives the data as a list of tuples (old format) or a dictionary (new format).
• Key Fallbacks: Chained .get() lookups for missing parameters to safely check for both the new missing_required_parameters key and the old missing_parameters key.

(Note: I saw there was another PR open for this, but I wanted to submit this approach as it handles the asl_parameters type mismatch (dict vs list) mentioned in the issue description!)

Fixes #38