1. The vendor dynamic table - done, both directions

PT_SCE_DYNLIBDATA and the DT_SCE_* tags: read by dynamic.rs, written by dynlib.rs, in both tag conventions.

2,200 lines describing one format, twice - the reason this repository exists - are now one implementation with tests on both sides of it. tests/module.rs links a real object with the repository's own script, builds a segment, installs it, and reads it back through the reader. (D025, D026)

What is deliberately not here: which library resolves a given name. That is a manifest, and it arrives as a closure.