fix: blockdb has block don't error if invalid block height

[DracoLi]

Why this should be merged

Fix the behaviour of HasBlock in x/blockdb. Currently if request a block below the min height of the database or a large block height that is not supported by the index file, then it returns an ErrInvalidBlockHeight error. Instead, we should just return false with no error as that makes more sense.

How this works

Treat both ErrInvalidBlockHeight and ErrBlockNotFound as expected errors for HasBlock

How this was tested

Add unit tests for HasBlock behaviour

Need to be documented in RELEASES.md?

[Copilot]

Pull Request Overview

This PR fixes the HasBlock method in the blockdb package to return false instead of an error when checking for blocks below the minimum height or above the maximum supported height. This change makes the API behavior more intuitive by treating out-of-range block heights as simply "not having" the block rather than throwing an error.

• Modified HasBlock to treat ErrInvalidBlockHeight the same as ErrBlockNotFound
• Added comprehensive unit tests covering edge cases including minimum height, maximum height, and missing blocks

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
x/blockdb/database.go	Updated HasBlock to handle invalid block heights as missing blocks
x/blockdb/readblock_test.go	Added comprehensive test cases for HasBlock behavior

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