feat(state): Add a AnyChainBlock state request for querying blocks in side chains

[arya2]

Motivation

Closes #10305.

Solution

• Adds a new request variant for querying block hashes in any chain
• Adds a new read fn in zebra-state for reading blocks from any chain

Related changes:

• Replaces some calls to with_watched_data() with calls to latest_best_chain()
• Adds a new method on WatchReciever to map the borrowed data to an owned value
• Updates latest_best_chain() to clone only the best chain and not the rest of the non-finalized state

Tests

Currently unused in Zebra and a trivial addition.

AI Disclosure

• No AI tools were used in this PR
• AI tools were used:

PR Checklist

• The PR name is suitable for the release notes.
• The PR follows the contribution guidelines.
• This change was discussed in an issue or with the team beforehand.
• The solution is tested.
• The documentation and changelogs are up to date.

[oxarbitrage]

Nice one.

[mergify]

Merge Queue Status

Rule: batched

---

• ✅ Entered queue — 2026-02-17 19:29 UTC
• ✅ Checks passed · on draft merge queue: embarking main (b581fba) and #10325 together #10328
• ✅ Merged — 2026-02-17 19:41 UTC · at 8b11e19012b149dba68c1c4fb31700ea7ea7c970

This pull request spent 11 minutes 18 seconds in the queue, including 29 seconds running CI.

Required conditions to merge

• #approved-reviews-by >= 1 [🛡 GitHub branch protection]
  • feat(state): Add a AnyChainBlock state request for querying blocks in side chains #10325
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  • feat(state): Add a AnyChainBlock state request for querying blocks in side chains #10325
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  • feat(state): Add a AnyChainBlock state request for querying blocks in side chains #10325
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  • feat(state): Add a AnyChainBlock state request for querying blocks in side chains #10325
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  • feat(state): Add a AnyChainBlock state request for querying blocks in side chains #10325
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