Bound Go symbol reader memory and add ELF comparison benchmarks

[brianrob]

Summary

• change Go symbol resolution to iterate through `.gopclntab` instead of loading the entire table
• bound reader memory to 196 KiB, independent of binary size
• simplify decoding around one shared cursor with two fixed read windows
• add reproducible Go fixtures and benchmarks comparing Go and ELF resolution

Performance

Using matched fixtures with 1,273 symbols:

Benchmark	ELF	Go	Result
Reader setup	29.39 µs	46.00 µs	Go setup is 1.57× slower
Full lifecycle	2.373 ms	153.82 µs	Go is 15.43× faster
Mapping resolution	2.656 ms	341.58 µs	Go is 7.78× faster
ELF+Go union mapping	2.656 ms ELF-only	2.877 ms union	8.32% overhead
Production resolution	3.128 ms unstripped ELF+Go	592.78 µs stripped Go	Stripped Go is 5.28× faster