Refactor and optimize code to address memory leaks and performance bottlenecks

[parvezk]

This commit refactors parts of src/index.js and src/utils.js to address performance bottlenecks, memory leaks, and XSS vulnerabilities. Changes include:

• Fixing tensor shape accesses to appropriately configure canvas dimensions.
• Changing map to forEach where array returns were unused.
• Securing showPredictions by switching from innerHTML to innerText.
• Resolving CPU bottlenecks and WebGL memory leaks by converting tensor operations inside hot loops to use Float32Array, wrapping sequence calls inside tf.tidy, and appropriately triggering .dispose() in .then() clauses of parallelized rendering tasks via Promise.all.

---

PR created automatically by Jules for task 4512242150080609377 started by @parvezk

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.