feat: Add Smart City Profile page (city-profile.html)

[Riya-Kharade]

📌 Description

This PR introduces a new Smart City Profile page to EcoPulse.

The page provides a comprehensive environmental dashboard for selected cities,
including air quality, water quality, noise levels, soil data, pollution trends,
and health impact insights.

closed #283

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✨ Changes Made

• Created new file: city-profile.html
• Added city selection dropdown
• Implemented pollution metric cards
• Added AQI severity classification
• Integrated Chart.js mini trend visualization
• Added health impact summary section
• Applied responsive eco-themed design
• Added navigation back to homepage

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🎯 Purpose

This feature:

• Adds city-level environmental intelligence
• Improves analytical depth
• Enhances data storytelling
• Strengthens hackathon and portfolio presentation
• Makes EcoPulse production-ready and smart-city oriented

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🧪 Testing

• Verified city selection updates data dynamically
• Tested chart rendering and update logic
• Checked severity classification
• Ensured responsive layout across devices

Screenshot

No backend changes were introduced.