fix(executor): filter debug-section labels from SymbolTable

[Oppen]

Summary

• SymbolTable::try_parse ignored st_shndx, letting debug-section local labels (.L0, .Lline_table_start*) in as fake functions
• these alias real .text addresses (assembler local-label reuse), so profiler lookups tied to a real symbol resolved to whichever entry sorted last
• reject symbols outside SHF_ALLOC sections and names starting with .

Illustration (recursion single-query profile, top functions by cycle count)

Before:

rank      cycles        %  function
   1   5200919000   99.37%  .L0
   2     12916576    0.25%  block_buffer::BlockBuffer<...>::digest_blocks::<...Keccak256Core...>
   3      5377972    0.10%  compiler_builtins::mem::memcpy
   4      5377972    0.10%  memcpy
   5      1576597    0.03%  memset

After:

rank      cycles        %  function
   1   3448394124   65.89%  keccak::keccak_p::<u64>
   2    433623582    8.29%  math::fft::bowers_fft::process_triple_fused_block::<...>
   3    317752655    6.07%  <sha3::Keccak256Core as digest::core_api::FixedOutputCore>::finalize_fixed_core
   4    238753357    4.56%  compiler_builtins::mem::memcpy
   5    219807702    4.20%  math::fft::bowers_fft::process_ifft_triple_fused_block::<...>

Test plan

• make test-profile-recursion-single — real functions now appear instead of .L0
• make lint
• make test — all pass except the 2 expected GPU test failures (no CUDA lib on this host)