Add mobile CSS tweaks for astrolabe and palace (max-width:480px)

[LeiShen929]

Motivation

• Adapt layout and typography for narrow screens (<=480px) to improve readability and reduce crowding in the astrolabe and palace components.
• Reduce spacing and scale down star/name typography for better fit on small phones.

Description

• Added @media (max-width: 480px) to src/Iztrolabe/Iztrolabe.css to reduce .iztro-astrolabe grid-gap from 3px to 2px.
• Added @media (max-width: 480px) to src/Izpalace/Izpalace.css to reduce .iztro-palace padding, adjust grid-template-rows, and tighten gaps/heights for .iztro-palace-adj, .iztro-palace-horo-star .stars, and .iztro-palace-fate.
• Added @media (max-width: 480px) to src/theme/default.css to lower --iztro-star-font-size-big/--iztro-star-font-size-small and tweak .iztro-palace-name .iztro-palace-name-taichi, .iztro-palace-center-item line-height, and .iztro-palace-fate span padding.

Testing

• No automated tests were executed for these CSS changes.

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Codex Task