[REFACTORING] many code uses hard coded `MapStyles[0]`

[JinIgarashi]

Refactoring Description

needs to refactoring where hard coding MapStyles[0]. This should refer to default map style setting from UserConfig.

Refacotring components

refactor the code where using MapStyles constant variable like MapStyles[0].uri

Refactoring Implementation

I am thinking to load MapStyles[0].uri at +layout.server.ts, so these code can be simplified a lot.

Refactoring Impact

No response

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