cleanup: drop resolved-issue citations from src comments

Sweep all src/**.zig comments that cite resolved issues (issue NNNN /
fix-NNNN / KB-N): the invariant or mechanism each comment states is
kept; the historical citation is dropped, per the no-conclusion-comments
rule. Pure-history parentheticals are removed outright. References to
the 16 still-open issues (0030, 0041-0056) are untouched, as are test
NAMES carrying regression provenance (matching the sanctioned
"Regression (issue NNNN)" example-header convention).

Also removes the issues/0019-import-non-transitive-c-scope/ fixture dir
— the issue is superseded and its behavior is covered by
examples/0706-modules-import-non-transitive.sx (the .md writeup stays).
issues/0030's repro .sx stays: that issue is an open feature request.

Gate: zig build OK; zig build test 426/426; run_examples 541/0; zero
expected/ snapshot churn.

src/ir/lower/expr.zig

@@ -472,7 +472,7 @@ pub fn lowerFieldAccess(self: *Lowering, fa: *const ast.FieldAccess, span: ast.S
     // const of the queried type (sibling of the identifier-receiver
     // intercepts above). Placed AFTER `Struct.CONST` so a user const named
     // `min`/`max` wins on its own struct; a builtin type name can never
-    // name a user struct (reserved — issue 0076), so they never collide.
+    // name a user struct (reserved), so they never collide.
     if (self.lowerNumericLimit(fa, span)) |ref| return ref;
 
     // M1.3 — `obj.class` on any Obj-C-class pointer lowers to
@@ -558,9 +558,9 @@ pub fn lowerFieldAccess(self: *Lowering, fa: *const ast.FieldAccess, span: ast.S
 /// constants `module_const_map`. The numeric-limit intercept must defer to
 /// ordinary field access whenever ANY of the three binds the name, so a
 /// raw value field read is never hijacked into a numeric-limit fold
-/// (issues 0092 local / 0093 global + module-const). A single helper used
+/// (locals, globals, and module-consts alike). A single helper used
 /// by both lowering and inference keeps the two resolvers in lockstep
-/// (issue-0083 two-resolver defect class).
+/// (two-resolver defect class).
 pub fn identifierBindsValue(self: *Lowering, name: []const u8) bool {
     if (self.scope) |scope| {
         if (scope.lookup(name) != null) return true;
@@ -600,7 +600,7 @@ pub fn lowerNumericLimit(self: *Lowering, fa: *const ast.FieldAccess, span: ast.
     // value is an ordinary field read, not a numeric-limit fold — defer to
     // the normal field-access path when the receiver identifier resolves to
     // a value binding through any of scope / globals / module consts
-    // (issues 0092, 0093). A `.type_expr` receiver is unambiguously a type
+    //. A `.type_expr` receiver is unambiguously a type
     // and can never be value-shadowed.
     if (fa.object.data == .identifier and self.identifierBindsValue(name)) return null;
 
@@ -684,7 +684,7 @@ pub fn lowerOptionalChain(self: *Lowering, obj: Ref, fa: *const ast.FieldAccess,
 /// aliases `.r`/`.g`/`.b`/`.a`) to its lane index. Returns null for any
 /// other field name so the read path (`lowerFieldAccessOnType`) and the
 /// write path (`lowerAssignment`) share one resolver and reject a
-/// non-lane field identically (issue 0086).
+/// non-lane field identically.
 pub fn vectorLaneIndex(field: []const u8) ?u32 {
     if (std.mem.eql(u8, field, "x") or std.mem.eql(u8, field, "r")) return 0;
     if (std.mem.eql(u8, field, "y") or std.mem.eql(u8, field, "g")) return 1;
@@ -1079,7 +1079,7 @@ pub fn lowerArrayLiteral(self: *Lowering, al: *const ast.ArrayLiteral) Ref {
         // aggregate array `[N]U` (lowerArrayLiteral always yields an array
         // value); materialize it into a `[]U` slice so the element is a real
         // {ptr,len} header rather than a raw array the callee would read its
-        // header off of (issue 0085). This per-element coercion recurses with
+        // header off of. This per-element coercion recurses with
         // the literal nesting, so `[][]T` and deeper coerce at every level.
         if (!elem_ty.isBuiltin()) {
             const ei = self.module.types.get(elem_ty);
@@ -1570,7 +1570,7 @@ pub fn lowerExpr(self: *Lowering, node: *const Node) Ref {
                 }
                 // F2: emit the SOURCE-AWARE author's value (own-wins), not the
                 // global last-wins `ci_global`. ≥2 flat-visible same-name const
-                // authors → a loud ambiguity (issue 0105 / 0760), never a silent
+                // authors → a loud ambiguity, never a silent
                 // pick. `.none` after a visible name is the registration-only
                 // author (no per-source partition) — emit its global value.
                 switch (self.selectModuleConst(id.name)) {
@@ -1607,7 +1607,7 @@ pub fn lowerExpr(self: *Lowering, node: *const Node) Ref {
                     const str = self.builder.constString(sid);
                     break :blk self.builder.boxAny(str, .string);
                 }
-                // fix-0102d site 2: taking a bare same-name fn as a VALUE
+                // taking a bare same-name fn as a VALUE
                 // (func_ref, fn-ptr / closure coercion) must capture the
                 // RESOLVED author's FuncId for a genuine flat collision, not
                 // the first-wins winner's. Plain bare name only; `.ambiguous`