chore: update blockdb to use HeightIndex interface and errors in database pkg

[DracoLi]

Why this should be merged

Follow up to #4133, update x/blockdb Database to align with the database.HeightIndex interface and use the errors from database/errors.go for database closed and not found.

How this works

• Renamed public methods WriteBlock, ReadBlock, and HasBlock to Put, Get, and Has
• Replaced ErrDatabaseClosed and ErrBlockNotFound with the common errors in database/errors.go
• Add HeightIndex dbtests to tests and aligned behaviour

How this was tested

Unit tests

Need to be documented in RELEASES.md?

No

[Copilot]

Pull Request Overview

This PR aligns the blockdb Database with the database.HeightIndex interface by renaming public methods and updating file naming conventions to be more generic rather than block-specific.

• Renamed public methods WriteBlock, ReadBlock, and HasBlock to Put, Get, and Has respectively
• Updated file naming from block-specific to generic (e.g., blockdb.idx to db.idx)
• Renamed BlockEntryVersion constant to DataEntryVersion to reflect generic data storage

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
x/blockdb/database.go	Core database implementation with method renames and constant updates
x/blockdb/writeblock_test.go	Test file updated to use new Put method instead of WriteBlock
x/blockdb/readblock_test.go	Test file updated to use new Get method instead of ReadBlock
x/blockdb/recovery_test.go	Recovery tests updated with new method names and DataEntryVersion constant
x/blockdb/datasplit_test.go	Data splitting tests updated to use new Put and Get methods
x/blockdb/database_test.go	Database tests updated with new method names

Comments suppressed due to low confidence (2)

x/blockdb/readblock_test.go:1

• The error message still references the old method name 'ReadBlock' but should be updated to 'Get' to match the renamed method.

// Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.

x/blockdb/recovery_test.go:1

• [nitpick] The error message refers to ErrBlockNotFound but this constant should likely be renamed to ErrDataNotFound or similar to align with the generic nature of the database as mentioned in the PR description.

// Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.

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[DracoLi]

Once #4212 is merged in. I'll also add the common interface tests to blockdb tests to ensure consistent behaviour.

[joshua-kim]

We test this behavior in TestWriteBlock_Basic that a block inserted via Put is returned through Get. It feels like we're duplicating coverage here, since it seems that this test is intended to verify heights.

Some ideas might be to either:

1. Refactor the tests to share the same test table, since it seems that testing the correctness of Put requires us to verify behavior on Get and the height apis
2. Remove this assertion entirely from this test, so we'd have a single test for Put/Get and one for Put/heights?

[DracoLi]

I think 2 makes sense here. The basic Put/Get tests should be covered and we can focus this tests on just the height verification. I'll remove this dup assertion to keep this tests more focused

[joshua-kim]

Sweet. We might also want to rename the tests here to reflect that the former is testing the contract between Put/Get and this one is testing the contract between Put/Height.