fix(glossary): same-id sources silently overwrite, hiding duplicates from validate and contradiction scan

[prakashUXtech]

What

Two glossary sources whose basenames collide derive the same article id and write the same wiki/<id>.md, so the second build silently overwrites the first. Example: glossary/pocket.md and docs/glossary/pocket.md (or any glossary file without an explicit id) both derive id = "pocket".

Why it matters

glossary validate's duplicate-term check runs over listArticles, which only ever sees the survivor of an overwrite — so it cannot catch a same-id duplicate. The cross-source contradiction scan (#19) inherits the same blind spot: it dedupes candidates on nameKey + sourceID, and same-id candidates share a sourceID, so a genuine conflict hidden behind an id collision never surfaces.

The distinct-id case (two different ids, same Term) is caught by both validate and the contradiction scan — that's the common one. This issue is specifically the same-id silent-overwrite case, which is already documented in the build hook comment as a known gap.

Fix options

• Warn at build time when two sources resolve to the same id, or
• Namespace glossary ids by source path so colliding basenames stay distinct.

Either closes the blind spot for both validate and the contradiction scan.