Switch to Material UI; replaced custom CSS/HTML with MUI components (no functional changes)

[koszti]

Warning

WARNING: This PR requires #21 to be merged first and rebase!

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Description

This PR replaces HTML and custom CSS with Material UI (MUI) components and theme styling. No functional/behavioral changes, this is a purely visual/layout refactor to make visual consistency of the app with the main Trino preview UI and other projects in the trino ecosystem.

What changed

• Replaced HTML markup and custom CSS styles with MUI components (AppBar, Box, Typography, Table, etc.).
• Centralized styling via the MUI theme for consistent spacing, typography, and colors
• Support dark and light theme
• Drop all custom CSS files

Screenshots

Additional context and related issues

Usage / Embedding
The editor is embeddable into other react projects, e.g.:

<QueryEditor theme="dark" height={800} />

Out of scope::

• Move legacy React patterns to modern hooks and idioms.
• Evaluate/transition to the official trino-js-client for server communication.

[sourcery-ai]

Sorry @koszti, your pull request is larger than the review limit of 150000 diff characters

[koszti]

@mosabua just a heads up - this works and I wanted to park it here as the next potential item to review. Let's make #21 ready first. It’s a large change because I couldn’t reasonably split. After all is now visually consistent with the preview UI by using material UI.