feat(lang): universal backtick raw identifier — valid in value, decl, AND type position [F0.6]

AGRA ruling (attempt 4): `` `name `` is THE LITERAL identifier `name`, usable in
EVERY position — the backtick only means "treat this token as a plain identifier,
never the reserved keyword/type", and is never part of the name's text.

- Raw in TYPE position is now VALID (reverses attempt-2 "raw is not a type"):
  `parseTypeExpr` emits a raw `type_expr`; `TypeResolver.resolveNamed` gains a
  `skip_builtin` flag (threaded from `te.is_raw` via lower.zig + type_bridge) so a
  `` `s2 `` reference resolves to a `` `s2 ``-declared type (struct/enum/union/alias),
  else a normal "unknown type 's2'" error (reportIfUnknownType skips the builtin
  exemption when raw). Bare `s2` in type position stays the builtin int.
- Every declaration-name site is is_raw-exemptible: `is_raw` added to TypeExpr +
  StructDecl/EnumDecl/UnionDecl/ErrorSetDecl/ProtocolDecl/ForeignClassDecl/UfcsAlias/
  NamespaceDecl/ImportDecl/CImportDecl/LibraryDecl; parser threads name_is_raw to
  every decl parse fn; namespace imports carry it through imports.addNamespace.
  Typed-const path (`` `s2 : s64 : 5 ``) now threads name_span+is_raw (fixes the
  1:1-caret bug).
- Check<->exemption made structurally symmetric: checkBindingName/checkDeclName take
  is_raw as a REQUIRED argument and skip inside the check, so no call site can
  validate a name without honoring the exemption (the desync cause of prior rounds).
- Bare reserved-name declarations of every kind still error (0076 preserved);
  `#import c` foreign names stay auto-raw + bare-callable.

specs.md + readme.md updated to the universal model. issue 0089 RESOLVED banner
rewritten. Examples: replace 1139 (raw-not-a-type) with 0154 (raw type reference);
add 0155 (typed const + union tag) and 1141 (bare type-decl negatives).
Gate: zig build + zig build test + run_examples (426 passed, 0 failed).

src/imports.zig

@@ -354,6 +354,7 @@ pub const ResolvedModule = struct {
         name: []const u8,
         other: ResolvedModule,
         span: ast.Span,
+        is_raw: bool,
     ) !void {
         const ns_node = try allocator.create(Node);
         ns_node.* = .{
@@ -361,6 +362,10 @@ pub const ResolvedModule = struct {
             .data = .{ .namespace_decl = .{
                 .name = name,
                 .decls = other.decls,
+                // Carry the backtick raw escape from the `name :: #import …`
+                // form so a reserved-name namespace is exempt from the decl
+                // check, symmetric to every other decl site (issue 0089).
+                .is_raw = is_raw,
             } },
         };
         try self.scope.put(name, {});
@@ -487,6 +492,7 @@ pub fn resolveImports(
                     .data = .{ .namespace_decl = .{
                         .name = ns_name,
                         .decls = try ns_decls.toOwnedSlice(allocator),
+                        .is_raw = ci.is_raw,
                     } },
                 };
                 ns_node.source_file = file_path;
@@ -569,7 +575,7 @@ pub fn resolveImports(
         };
 
         if (imp.name) |ns_name| {
-            try mod.addNamespace(allocator, &decl_list, &own_decl_list, &seen_in_list, ns_name, imported_mod, decl.span);
+            try mod.addNamespace(allocator, &decl_list, &own_decl_list, &seen_in_list, ns_name, imported_mod, decl.span, imp.is_raw);
         } else {
             try mod.mergeFlat(allocator, &decl_list, &seen_in_list, &seen_nodes, imported_mod);
         }