fix: make additives and nutrient level attributes clickable (#8492)

[sarthaklole]

What

This PR updates lib/ProductOpener/Attributes.pm to make additives and nutrient level product attributes clickable by assigning appropriate panel_id properties for knowledge panel navigation.

Specifically:

• Additives attribute:
  • Links to additives when additives exist (additives_n > 0).
  • Links to ingredients when no ingredients text is present (so users get an action to add ingredients).
  • Links to ingredients_analysis when ingredients exist but 0 additives are found or status is unknown.
• Nutrient level attributes (low_fat, low_salt, low_sugars, low_saturated_fat):
  • Links to nutrient_level_<nid> (e.g., nutrient_level_fat) when nutrient levels are known.
  • Links to nutrition_facts_table when nutrient levels are unknown.

Large Language Models usage disclosure

• Used Google Antigravity AI Assistant (Gemini 3.6 Flash) in agentic pair-programming mode to analyze existing panel linking patterns from PR fix: add more linked panels for attributes #6808, locate attribute definitions in lib/ProductOpener/Attributes.pm, and update panel_id assignment logic.

Related issue(s) and discussion

• Fixes Make additives & nutrition related attributes clickable  #8492

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud