feat: filter governance events by address

[wolf31o2]

Closes #490

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Summary by cubic

Add address-based filtering for Cardano governance events. This surfaces only proposals, treasury withdrawals, and vote delegations tied to the configured addresses.

• New Features
  • Match proposal RewardAccount against stake addresses.
  • Match treasury withdrawal recipients against payment or stake addresses.
  • Match vote delegation certificates by stake credential hash (handles header-byte cases).
  • Apply address filter in governance event pipeline; added unit tests for pass/fail cases.

^{Written for commit 78b62b8. Summary will update on new commits.}

Summary by CodeRabbit

• New Features

  • Governance event filtering now supports matching by reward accounts, treasury withdrawal addresses (payment and stake forms), and stake credential hashes.

• Tests

  • Added comprehensive tests covering reward account matches, treasury withdrawal cases, stake credential hash matching, and negative/no-address scenarios.

[coderabbitai]

📝 Walkthrough

Walkthrough

This change adds address filtering for Cardano governance events by introducing matchAddressFilterGovernance(ge event.GovernanceEvent) bool. The filter checks proposal reward accounts, treasury withdrawal addresses (payment and stake), and stake credential hashes (hex-decoded, with last 28 bytes considered) against configured address filters. filterGovernanceEvent now calls this method when address filters are present. Hex decoding support was added and tests covering multiple governance address scenarios were included.

Possibly related PRs

• blinklabs-io/adder PR 578: Introduces the GovernanceEvent type and related chainsync emission used by the new governance-address filtering logic.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: filter governance events by address' is concise, specific, and directly describes the main change in the changeset.
Linked Issues check	✅ Passed	The PR implements address-based filtering for governance events, covering proposals, treasury withdrawals, and vote delegations as required by issue #490.
Out of Scope Changes check	✅ Passed	All changes are focused on governance event address filtering; no unrelated modifications detected.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/filter-gov-by-addr

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[cubic-dev-ai]

No issues found across 2 files

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@filter/cardano/cardano.go`:
- Around line 232-244: matchStakeCertificates is comparing 28-byte credBytes to
entries in stakeCredentialHashes that include a 1-byte header (29 bytes), so the
equality check always fails; update matchStakeCertificates to mirror the logic
in matchAddressFilterGovernance: for each filterHash from stakeCredentialHashes,
if len(filterHash) > 28 set hashToCompare = filterHash[len(filterHash)-28:] else
hashToCompare = filterHash, then compare bytes.Equal(credBytes, hashToCompare);
this ensures header-byte handling is consistent between
matchAddressFilterGovernance and matchStakeCertificates.