[codex] Align WendaoCodeParser with PureHTTP2 transport locks

[GTrunSec]

Summary

• align parser transport locks with the current WendaoArrow PureHTTP2 lane
• fix dense parser-summary partition schema stability for nullable columns
• remove deprecated JuliaSyntax usage and keep package-owned CI/test bootstrap on Project.toml locks

Validation

• direnv exec "$PRJ_ROOT" julia --project=.data/WendaoCodeParser.jl -e 'using Pkg; Pkg.resolve(); Pkg.instantiate(); Pkg.build(); Pkg.test("WendaoCodeParser"; coverage=false, julia_args=--depwarn=error)'