perf(build): switch build optimization from ReleaseSafe to ReleaseFast

[hendriknielaender]

This pull request changes the build optimization mode for the Zig Version Manager (zvm) from ReleaseSafe to ReleaseFast. The ReleaseFast mode prioritizes performance by removing safety checks, making it more suitable for production use where maximum efficiency is desired.

Benchmark Results

Benchmarks were conducted using hyperfine to compare the performance of ReleaseSafe and ReleaseFast builds. Here are the results for various commands:

Command	ReleaseFast Time (mean ± σ)	ReleaseSafe Time (mean ± σ)	Speed Improvement
zvm --help	4.4 ms ± 2.4 ms	4.6 ms ± 1.1 ms	1.06× faster
zvm -v	4.6 ms ± 1.1 ms	5.1 ms ± 1.0 ms	1.11× faster
zvm ls	657.9 ms ± 23.9 ms	731.6 ms ± 33.9 ms	1.11× faster
zvm ls --system	4.6 ms ± 1.0 ms	6.3 ms ± 1.1 ms	1.35× faster

Observations

• Across all tested commands, the ReleaseFast build consistently outperformed the ReleaseSafe build.

Warnings

• Commands with execution times under 5 ms may have inaccuracies due to shell startup time calibration limitations. These results should still reflect relative performance differences.

Justification for Change

• Faster command execution aligns with user expectations for a CLI tool.
• The lack of safety checks in ReleaseFast is acceptable.