fix(utils): handle rounding of small trend values

[hanna-skryl]

Fixes #804

This PR replaces Math.round() with the custom roundValue function to handle rounding of score and value changes.

Previously, scores could be floats rounded to one decimal place, while values were always rounded to whole numbers. With the new roundValue function, both scores and values are now consistently rounded to their first decimal, ensuring uniform and accurate rounding throughout.

[github-actions]

Code PushUp

🤨 Code PushUp report has both improvements and regressions – compared target commit b20e518 with source commit 3dde651.

🕵️ See full comparison in Code PushUp portal 🔍

🏷️ Categories

🏷️ Category	⭐ Previous score	⭐ Current score	🔄 Score change
Performance	🟡 54	🟡 53
Code coverage	🟡 90	🟡 90
Custom checks	🟡 67	🟡 67	–
Security	🟡 84	🟡 84	–
Updates	🟡 78	🟡 78	–
Accessibility	🟢 91	🟢 91	–
Best Practices	🟢 100	🟢 100	–
SEO	🟡 61	🟡 61	–
Bug prevention	🟢 100	🟢 100	–
Code style	🟢 99	🟢 99	–

👍 1 group improved, 👎 1 group regressed, 👍 3 audits improved, 👎 4 audits regressed, 12 audits changed without impacting score

🗃️ Groups

🔌 Plugin	🗃️ Group	⭐ Previous score	⭐ Current score	🔄 Score change
Lighthouse	Performance	🟡 54	🟡 53
Code coverage	Code coverage metrics	🟡 90	🟡 90

18 other groups are unchanged.

🛡️ Audits

🔌 Plugin	🛡️ Audit	📏 Previous value	📏 Current value	🔄 Value change
Lighthouse	Speed Index	🟥 5.9 s	🟥 6.4 s
Lighthouse	First Contentful Paint	🟨 2.9 s	🟥 3.1 s
Lighthouse	First Meaningful Paint	🟨 2.9 s	🟨 3.1 s
Lighthouse	Time to Interactive	🟥 14.5 s	🟥 16.6 s
Code coverage	Branch coverage	🟨 84.7 %	🟨 84.7 %
Code coverage	Function coverage	🟩 92.1 %	🟩 92.1 %
Code coverage	Line coverage	🟩 91.9 %	🟩 91.9 %
Lighthouse	Minimizes main-thread work	🟥 15.0 s	🟥 19.9 s
Lighthouse	Avoids enormous network payloads	🟩 Total size was 1,835 KiB	🟩 Total size was 1,838 KiB
Lighthouse	JavaScript execution time	🟥 6.9 s	🟥 9.3 s
Lighthouse	Metrics	🟩 100%	🟩 100%
Lighthouse	Total Blocking Time	🟥 4,600 ms	🟥 6,670 ms
Lighthouse	Uses efficient cache policy on static assets	🟨 27 resources found	🟨 27 resources found
Lighthouse	Eliminate render-blocking resources	🟥 Potential savings of 1,200 ms	🟥 Potential savings of 620 ms
Lighthouse	Max Potential First Input Delay	🟥 2,470 ms	🟥 2,820 ms
Lighthouse	Initial server response time was short	🟩 Root document took 440 ms	🟩 Root document took 510 ms
Lighthouse	Server Backend Latencies	🟩 200 ms	🟩 250 ms
Lighthouse	Network Round Trip Times	🟩 80 ms	🟩 60 ms
Lighthouse	Largest Contentful Paint	🟨 3.1 s	🟨 3.1 s

494 other audits are unchanged.