A2-merge gate: both parts in one commit, behavior-preserving (350/0).
Part 1 — retire the TypeTable.aliases borrow (build-enforced):
- type_bridge.zig: add `AliasMap` and thread it as an explicit param through
every name-resolving fn (resolveAstType, bridgeType, resolveTypeName, the
compound resolvers, resolveTupleLiteralAsType, resolveParameterizedType, the
inline enum/struct/union + error resolvers). resolveTypeName now forwards the
threaded map to TypeResolver.resolveNamed instead of reading table.aliases.
- lower.zig: all 31 resolveAstType callers pass
&self.program_index.type_alias_map; drop the lowerRoot loan.
- types.zig: remove the now-unused TypeTable.aliases field.
- type_bridge.test.zig: alias test passes alias_map explicitly; other calls
pass null.
Part 2 — pack projections get one owner + no .void failure sentinel:
- New packs.zig (PackResolver, a *Lowering facade): moves
resolveClosure/Tuple/FunctionTypeWithBindings, packTypeElems, packTypeArgs,
elementProtocolTypeArg out of Lowering. Call sites route through
Lowering.packResolver(); barrel-wired in ir.zig.
- The missing-projection `orelse .void` in packTypeArgs now emits a diagnostic
and fills the slot with .unresolved (the tripwire sentinel), never a real
.void; OOM `catch return .void` in the moved fns became .unresolved too.
Legitimate no-return-type `else .void` defaults are preserved.
- packs.test.zig: packTypeArgs bound/unbound/no-constraint/no-state cases +
the missing-projection backstop (diagnostic + .unresolved slot).
3ed1b3a7a0