ident: make Name's inner Vec private

[pcnofelt]

What

Makes Name's inner Vec<String> private.
Addresses linear issue IM-55

Why

Name assumes it always has at least one label. FromStr enforces that, but the public tuple field let callers write Name(vec![]) directly and bypass validation, which could lead to a runtime panic in helpers like first_label(). Making the field private closes that gap, so the invariant holds by construction.

Changes

• src/ident.rs: make the inner Vec private and switch first_label() from expect() to the local assert() helper.
• src/modules/adhoc.rs: use label_count() instead of reading .0 directly.
• src/trust_engine_bench/node.rs: build derived names through parsing instead of pushing onto the raw Vec.
• context/interfaces/src/ident.md: document Name as opaque.

After this change, code outside src/ident.rs no longer constructs Name(...) or reads .0.

🤖 Generated with Claude Code