feat(gnoland): add block_height and chain_id to GnoTxMetadata

[moul]

Summary

• Extends GnoTxMetadata with BlockHeight (int64) and ChainID (string) fields, both with omitempty for backward compatibility
• Updates genesis replay ContextFn in loadAppState to also apply block height from metadata during genesis tx execution
• Adds TestInitChainer_MetadataBlockHeight test verifying block height is correctly set during genesis replay

Context

Part of the chain upgrade (gnoland1 → gnoland-1) tx export/import pipeline. These fields allow preserving the original block height and chain ID when exporting transactions for genesis assembly.

Companion PR: gnolang/tx-archive — backup populates these new fields, plus new genesis-assemble command.

Related PRs: #5334, #5368, #5376, #5377

Test plan

• TestInitChainer_MetadataBlockHeight passes — deploys a realm capturing runtime.ChainHeight() at genesis, verifies captured height matches metadata
• Existing TestInitChainer_MetadataTxs still passes
• Verify omitempty — old JSONL files without new fields still deserialize correctly

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[aeddi]

Are you planning to use the ChainID field in a future PR? As it stands, it looks like dead code.

I see it’s being populated on the tx-archive side, but I don’t really get the goal there either (looks like it's never read). Maybe your intent is to specify where a TX comes from in each jsonl line? If that's the goal, I’m wondering if just defining it at the file level would be enough, so we don't unnecessarily duplicate the same data on every line of the jsonl.

Either way, it’d be good to add a comment explaining why this field is there.

[moul]

The goal is to ensure the exported value is complete for validating signatures and replaying under similar conditions. We aim to use it as soon as it makes sense, but we want to make it available now to ensure completeness.

[moul]

Closing this PR as it is superseded by #5411. The BlockHeight and ChainID fields added here are now part of GnoTxMetadata in #5411, which is the main hardfork framework PR. The hardfork genesis tool (misc/hardfork) reads these fields directly when assembling the genesis.