perf: Replace SmallVec with custom storage

[CathalMullan]

No description provided.

[codspeed-hq]

Merging this PR will improve performance by 13.55%

⚡ 70 improved benchmarks
❌ 5 (👁 5) regressed benchmarks
✅ 129 untouched benchmarks

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	wildcard_nested[10]	4.4 µs	3.2 µs	+35.9%
⚡	Simulation	wildcard_nested_triple[10]	4.5 µs	3.3 µs	+35.33%
⚡	Simulation	wildcard_nested_present[10]	4.4 µs	3.2 µs	+35.12%
⚡	Simulation	wildcard_depth[1]	696.1 ns	517.8 ns	+34.44%
⚡	Simulation	wildcard_nested_inline[10]	4.5 µs	3.3 µs	+34.1%
⚡	Simulation	wildcard_open[1]	4 µs	3 µs	+33.83%
⚡	Simulation	wildcard_open[10]	4.1 µs	3.1 µs	+32.48%
⚡	Simulation	wildcard_backtrack[10]	4 µs	3.1 µs	+28.55%
⚡	Simulation	wildcard_nested_triple[100]	6.4 µs	5 µs	+27.46%
⚡	Simulation	wildcard_nested_inline[100]	6.4 µs	5 µs	+27.43%
⚡	Simulation	dynamic_depth[1]	696.1 ns	546.9 ns	+27.27%
⚡	Simulation	wildcard_nested[100]	6.4 µs	5 µs	+27.26%
⚡	Simulation	wildcard_nested_present[100]	6.4 µs	5 µs	+27.08%
⚡	Simulation	wildcard_backtrack[1000]	4.9 µs	3.9 µs	+27.07%
⚡	Simulation	wildcard_backtrack[100]	5 µs	3.9 µs	+26.88%
⚡	Simulation	wildcard_open[100]	6 µs	4.7 µs	+26.45%
⚡	Simulation	wildcard_nested[1]	697.8 ns	577.8 ns	+20.77%
⚡	Simulation	wildcard_nested_inline[1]	697.8 ns	577.8 ns	+20.77%
⚡	Simulation	wildcard_nested_present[1]	697.8 ns	577.8 ns	+20.77%
⚡	Simulation	wildcard_nested_triple[1]	697.8 ns	577.8 ns	+20.77%
...	...	...	...	...	...

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

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing stash (94f89ad) with main (2e926f7)}

[codecov]

Codecov Report

❌ Patch coverage is 99.35484% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/needle.rs	91.66%	0 Missing and 1 partial ⚠️

Files with missing lines	Coverage Δ
src/node.rs	96.58% <100.00%> (-0.04%)	⬇️
src/router.rs	100.00% <100.00%> (ø)
src/storage.rs	100.00% <100.00%> (ø)
src/needle.rs	96.55% <91.66%> (-3.45%)	⬇️