A 'Unit.Symbol' reference must resolve against that specific unit's
exports — never the flat global table or the uses chain — so a
same-named symbol in another used unit can neither shadow it nor be
shadowed by it. Previously the unit prefix was discarded at three
independent sites (idents, type names, statement targets), collapsing
every qualified reference to a bare lookup; a shadowed const/type in an
earlier-in-uses unit was then unreachable even when named explicitly.
Introduce a single directed-lookup primitive, ResolveQualified(Unit,
Name): per-unit cache first (the authoritative map of what each unit
exported, where a cross-unit collision loser is retained after being
evicted from the flat table), then a lenient flat-table fallback for
harnesses that populate the global but not the cache. Route the three
sites through it: the parser now preserves the matched unit on
TIdentExpr.QualifierUnit (serialised into the .bif), the type resolver
consults it for dotted type names, and a unit-qualified class ancestor
'class(Unit.TParent)' resolves through the type machinery so inheritance
binds to the named unit's type.
The const last-wins path now stashes the shadowed const in the per-unit
cache (it claimed to but never did), so 'Unit.Const' reaches the
declaring unit's own value regardless of which unit won the bare slot.
Parent/implements names parse via ParseTypeName (which already absorbs
the unit qualifier and nested generics) instead of ParseGenericName.
Tests: qualified-const disambiguation (ua.Foo=100 / ub.Foo=200 read
independently of the bare last-wins winner) and qualified inheritance
(class(ua.TParent) inherits across units).
c7f264acec