ci(codspeed): add memory, walltime and Python benchmark jobs

[bug-ops]

Summary

Add comprehensive CodSpeed benchmark coverage with multiple instruments:

• Simulation (existing): CPU instruction counting for deterministic results
• Memory: Heap allocation tracking for memory profiling
• Walltime: Real execution time measurement
• Python: pytest-codspeed integration for Python benchmarks

Changes

• Add memory profiling job with mode: instrumentation and instruments: memory
• Add walltime job with mode: walltime for real-time measurements
• Add Python benchmark job using pytest-codspeed
• Add pytest-codspeed to benchmark dependencies in pyproject.toml

Documentation references

• Memory instrument: https://codspeed.io/docs/instruments/memory
• Walltime instrument: https://codspeed.io/docs/instruments/walltime
• Python benchmarks: https://codspeed.io/docs/benchmarks/python

Test plan

• All CodSpeed jobs run successfully
• Benchmark results appear in CodSpeed dashboard

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@           Coverage Diff           @@
##             main      #88   +/-   ##
=======================================
  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]

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing feature/codspeed-memory-walltime (036fbe3) with main (7d02d61)}

⚠️ 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.

Summary

✅ 137 untouched benchmarks
🆕 324 new benchmarks

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
🆕	WallTime	get_no_ttl_check	N/A	166 ns	N/A
🆕	WallTime	direct_inmemory_get	N/A	166 ns	N/A
🆕	WallTime	key_creation_query_result	N/A	143 ns	N/A
🆕	WallTime	factory_single_builder_large_binary	N/A	113 ns	N/A
🆕	WallTime	size_bytes[1000]	N/A	3.8 µs	N/A
🆕	WallTime	size_bytes[10000]	N/A	33.5 µs	N/A
🆕	WallTime	size_bytes[1000000]	N/A	15.8 ms	N/A
🆕	WallTime	traced_cache_get	N/A	188 ns	N/A
🆕	WallTime	columns[50]	N/A	3.6 ms	N/A
🆕	WallTime	concurrent_mixed[1]	N/A	54.4 µs	N/A
🆕	WallTime	factory_single_builder_time64	N/A	70 ns	N/A
🆕	WallTime	read_heavy[2]	N/A	93.9 µs	N/A
🆕	WallTime	compute_stats[10]	N/A	47 ns	N/A
🆕	WallTime	batch_sizes[1024]	N/A	725.9 µs	N/A
🆕	WallTime	time64_nulls	N/A	85.4 µs	N/A
🆕	WallTime	list_tables_memory_miss	N/A	11.5 µs	N/A
🆕	WallTime	int64_conversion[100000]	N/A	658.7 µs	N/A
🆕	WallTime	analytics_1m_rows	N/A	69.3 ms	N/A
🆕	WallTime	len[100]	N/A	112.2 µs	N/A
🆕	WallTime	entries[100]	N/A	38.1 µs	N/A
...	...	...	...	...	...

ℹ️ Only the first 20 benchmarks are displayed. Go to the app to view all benchmarks.