fix(menu): restore Add button hover state (#80)

[vaibhavis9024]

Title: fix(menu): restore Add button hover state (#80)

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Summary

Restores the missing hover state on the Add button across all product cards.

Fixes #80

Problem

On every product card in Today's Specials, Recently Viewed, and Explore Our Menu, hovering the Add button produced no visual feedback. The CSS hover rule was defined but never had any effect.

Root cause

createCard() in js/main.js was rendering the button with an inline style="background-color: …" attribute. Inline style declarations win over external CSS for the same property, so the inline background-color was overriding the :hover rule's background change on every hover event.

The class-name mismatch called out in the issue (btn-add in CSS vs add-btn in JS) is real but is a separate orange-theme leftover — the maintainer has confirmed the green color is intentional, so this PR does not touch that path.

Fix

Remove the inline style attribute (and the now-unused buttonColor variable that fed it) from the createCard() template. The existing CSS then takes over on its own:

• .card-footer .add-btn paints the available button green (#2e7d32)
• .card-footer .add-btn:hover darkens it to #1b5e20 with the shadow and 1px lift
• .add-btn:disabled { background-color: #cccccc !important; } keeps out-of-stock items grey

Theme preserved

Per the maintainer's note that the off-theme green is intentional, the button color is unchanged. This PR only restores the missing hover transition.