feat(base-mereology, base-query): add Composites.verify and Index.reindex

[deer]

• Composites.verify(root, suspect) — walks the transitive composition of a Composite (including the root) and returns every reachable Composite that matches the caller-supplied predicate but exposes no parts. Catches the class of bug fixed in fix(expression-codemodel): implement otherParts() for Literal and TemplateExpression codemodel.build#54 before it silently corrupts TypeReference derivation. Three tests cover the no-suspects path, the flagging path, and predicate filtering.
• Index.reindex(object) — default method on Index that unindexes then re-indexes an object. Replaces the hand-rolled unindex/index pair that CodeModelTraitable currently repeats at every trait mutation site. One test in IndexCompatibilityTests verifies that a mutated @Indexable value is reflected correctly after a reindex call.