chore: clean up code

[Boshen]

Summary

• Use char literals instead of string literals for single characters
• Replace match with if/else for simple boolean checks
• Remove unnecessary string cloning (.to_owned())
• Simplify conditional logic with is_some_and()
• Use Vec::new() instead of [].to_vec()
• Use String::new() instead of String::from("")
• Use unwrap_or_default() instead of unwrap_or_else(|| "".to_string())
• Use string interpolation shorthand in format macros
• Simplify Default trait usage

Test plan

• All existing tests pass
• Clippy passes with no warnings

🤖 Generated with Claude Code

[github-actions]

Benchmark for 9b20ac4

Click to view benchmark

Test	Base	PR	%
vpath_edge_cases	2.1±0.07µs	2.1±0.08µs	0.00%
vpath_mixed_workload	4.5±0.15µs	4.4±0.17µs	-2.22%
vpath_native	1300.9±40.88ns	1283.3±66.03ns	-1.35%
vpath_virtual	3.3±0.12µs	3.4±0.12µs	+3.03%
vpath_virtual_zip	2.7±0.08µs	2.8±0.10µs	+3.70%
vpath_zip	1917.7±112.27ns	1879.1±71.00ns	-2.01%

[github-actions]

Benchmark for 3225390

Click to view benchmark

Test	Base	PR	%
vpath_edge_cases	2.1±0.07µs	2.1±0.08µs	0.00%
vpath_mixed_workload	4.5±0.14µs	4.6±0.13µs	+2.22%
vpath_native	1330.1±34.84ns	1332.9±70.27ns	+0.21%
vpath_virtual	3.3±0.14µs	3.4±0.17µs	+3.03%
vpath_virtual_zip	2.8±0.07µs	2.9±0.11µs	+3.57%
vpath_zip	1832.1±62.59ns	1885.0±84.09ns	+2.89%