fix(sei-db): fix flaky RocksDB parallel iteration test

[pdrobnjak]

Summary

• Fixes a use-after-free race condition in the RocksDB iterator that caused TestDatabaseParallelIterationVersions to flake
• The ReadOptions object (and its timestamp slice) created by newTSReadOptions() was passed to NewIteratorCF() but never stored, making it eligible for GC while the C++ iterator still held a dangling Slice pointer to the timestamp data
• Under parallel access (99 goroutines in the test), GC pressure caused iterators to read with corrupted timestamps, returning values from wrong versions (e.g., expected val002-011 but got val002-017)
• The fix stores ReadOptions in the iterator struct and calls Destroy() on Close(), ensuring the timestamp data remains valid for the iterator's lifetime
• Also fixes the same ReadOptions leak in getSlice() (used by Get/Has)

Test plan

• TestDatabaseParallelIterationVersions — the previously flaky test should now pass consistently
• All other RocksDB tests unaffected (no API changes beyond the internal plumbing)

🤖 Generated with Claude Code

[github-actions]

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Feb 19, 2026, 8:58 PM

[codecov]

Codecov Report

❌ Patch coverage is 96.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 57.70%. Comparing base (8cf29d8) to head (f2d7ae3).

Files with missing lines	Patch %	Lines
sei-db/db_engine/rocksdb/mvcc/db.go	90.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2928       +/-   ##
===========================================
- Coverage   68.42%   57.70%   -10.72%     
===========================================
  Files           5     2111     +2106     
  Lines         456   174218   +173762     
===========================================
+ Hits          312   100532   +100220     
- Misses        114    64698    +64584     
- Partials       30     8988     +8958     

Flag	Coverage Δ
sei-chain	57.67% <ø> (?)
sei-db	69.18% <96.66%> (+0.75%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
sei-db/db_engine/rocksdb/mvcc/iterator.go	86.31% <100.00%> (+0.76%)	⬆️
sei-db/db_engine/rocksdb/mvcc/db.go	58.23% <90.00%> (+0.91%)	⬆️

... and 2106 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.