chore(release): v0.3.4

[bug-ops]

Summary

Patch release v0.3.4 with CodSpeed benchmarking integration and infrastructure improvements.

Changes

• CodSpeed Integration: 4-mode continuous benchmarking (simulation, memory, walltime, Python)
• Phase 4: Prometheus metrics infrastructure for hdbconnect-mcp
• Phase 4.5: Configuration reload with lock-free reads via arc-swap
• CI: Migrated to moonrepo/setup-rust for unified toolchain management
• Tests: Improved code coverage to ~87%

Commits since v0.3.3

• ci(codspeed): add memory, walltime and Python benchmark jobs
• ci: migrate to moonrepo/setup-rust for unified toolchain management
• test: improve code coverage with unit tests
• ci(codspeed): add benchmark workflow with required features
• feat(mcp): Phase 4.5 - Configuration reload infrastructure
• feat(mcp): Phase 4 - Prometheus metrics infrastructure

Checklist

• Version bumped in Cargo.toml (workspace)
• Version bumped in python/pyproject.toml
• CHANGELOG.md updated
• All CI checks pass

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@           Coverage Diff           @@
##             main      #89   +/-   ##
=======================================
  Coverage   86.64%   86.64%           
=======================================
  Files          63       63           
  Lines       13349    13349           
=======================================
  Hits        11566    11566           
  Misses       1783     1783           

Flag	Coverage Δ
hdbconnect-arrow	86.59% <ø> (ø)
hdbconnect-mcp	86.59% <ø> (ø)
python	100.00% <ø> (ø)

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[codspeed-hq]

Merging this PR will degrade performance by 21.9%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚡ 8 improved benchmarks
❌ 8 regressed benchmarks
✅ 445 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	WallTime	noop_get	17 ns	19 ns	-10.53%
❌	WallTime	concurrent_mixed[2]	74.7 µs	85.1 µs	-12.28%
⚡	WallTime	len[1000]	539.4 µs	354.5 µs	+52.18%
⚡	WallTime	size_bytes[10000]	496.9 µs	410.4 µs	+21.08%
❌	WallTime	factory_single_builder_large_utf8	106 ns	125 ns	-15.2%
⚡	WallTime	size_bytes[1000]	42.8 µs	38.2 µs	+11.9%
❌	WallTime	get[4096]	251 ns	284 ns	-11.62%
❌	WallTime	factory_single_builder_large_binary	107 ns	137 ns	-21.9%
⚡	WallTime	size_bytes[100000]	478 µs	415.1 µs	+15.16%
❌	WallTime	columns[100]	6.7 ms	7.7 ms	-12.45%
⚡	WallTime	list_tables_miss_db1000us[50_tables]	2 ms	1.6 ms	+23.44%
⚡	WallTime	size_bytes[100000]	481.8 µs	418.1 µs	+15.22%
❌	WallTime	int64_1m_rows	9.7 ms	10.7 ms	-10%
⚡	WallTime	deserialize_100_tables	16.9 µs	13.2 µs	+28.28%
⚡	Memory	same_key_contention[4]	11.9 KB	10.7 KB	+10.93%
❌	Memory	concurrent_get[4]	716 B	810 B	-11.6%

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_{Comparing chore/release-0.3.4 (035effc) with main (e66dda0)}