issues: relocate legacy examples/issue-* repros into issues/

Clear the examples/issue-* namespace (new layout keeps open-issue repros under
issues/, co-located with their .md). Two legacy files:

- issue-0030 was a feature-request placeholder (trivial main, no real test).
  `extern G : T;` cross-file sx globals are still unimplemented (parse error),
  so it's an open feature request: issues/0030-extern-global-declarations.{md,sx}.
- issue-0019 was a broken/superseded multi-file fixture (relative imports, not
  runnable from root; the non-transitive-#import scenario is covered by the
  passing 0706-modules-import-non-transitive). Moved to
  issues/0019-import-non-transitive-c-scope/ with a status note; safe to delete.

Suite unchanged: 324 passed.

issues/0019-import-non-transitive-c-scope.md

@@ -0,0 +1,27 @@
+# 0019 — `#import` is non-transitive (C-function scope across files)
+
+> **Status: superseded — kept for reference.** Relocated from the old
+> `examples/issue-0019/` fixture during the test-layout migration. The behavior
+> it probed (A imports B and C; C must NOT see B's `#foreign` C functions just
+> because A imported B) is now covered by the passing test
+> `examples/0706-modules-import-non-transitive.sx`.
+
+## What it probed
+
+`main` imports both `c_wrapper.sx` (which declares C `#foreign` functions) and
+`other.sx`. `other.sx` should *not* gain access to `c_wrapper`'s C functions
+transitively — using one should produce the "not visible; #import the module that
+declares it" diagnostic.
+
+- `main_good.sx` — the valid arrangement.
+- `main_bad.sx` — the arrangement that must be rejected.
+- `c_wrapper.sx`, `other.sx` — the imported modules.
+
+## Caveat (why it doesn't run as-is)
+
+The fixture uses **relative** imports (`#import "../modules/std.sx"`), which only
+resolve relative to a specific working directory and violate the project's
+"always `package:`/module-path imports, never relative" rule. It is not runnable
+from the repo root and is not wired into the suite. If revived, rewrite the
+imports to the standard `modules/...` form and pin expected output; otherwise it
+can be deleted (the scenario is already covered by `0706-modules-import-non-transitive`).

issues/0019-import-non-transitive-c-scope/c_wrapper.sx

@@ -0,0 +1,10 @@
+// This module imports C functions and provides wrappers
+#import c {
+    #include "vendors/test_c/test.h";
+    #source "vendors/test_c/test.c";
+};
+
+// Wrapper function that calls the C function
+wrapped_add :: (a: s32, b: s32) -> s32 {
+    add_numbers(a, b);
+}

issues/0019-import-non-transitive-c-scope/main_bad.sx

@@ -0,0 +1,18 @@
+// Test: other.sx calls C functions without importing the C module
+// main imports both c_wrapper.sx and other.sx
+// other.sx should NOT have access to C functions from c_wrapper
+#import "../modules/std.sx";
+#import "c_wrapper.sx";
+#import "other.sx";
+
+main :: () -> s32 {
+    // This works: we import c_wrapper so we have transitive access
+    result := wrapped_add(10, 20);
+    print("wrapped_add(10, 20) = {}\n", result);
+
+    // This calls other.sx's function which tries to call add_numbers
+    // other.sx did NOT import c_wrapper.sx, so this should fail
+    bad := use_c_directly();
+    print("use_c_directly() = {}\n", bad);
+    0;
+}

issues/0019-import-non-transitive-c-scope/main_good.sx

@@ -0,0 +1,10 @@
+// Test: calling wrapper functions works (we import the module)
+#import "../modules/std.sx";
+#import "c_wrapper.sx";
+
+main :: () -> s32 {
+    // This should work: calling the sx wrapper
+    result := wrapped_add(10, 20);
+    print("wrapped_add(10, 20) = {}\n", result);
+    0;
+}

issues/0019-import-non-transitive-c-scope/other.sx

@@ -0,0 +1,6 @@
+// This file does NOT import c_wrapper.sx
+// It should NOT be able to call add_numbers
+
+use_c_directly :: () -> s32 {
+    add_numbers(5, 3);
+}

issues/0030-extern-global-declarations.md

@@ -0,0 +1,63 @@
+# 0030 — `extern G : T;` cross-file sx global declarations (feature request)
+
+> **Status: OPEN feature request** (not a bug). Relocated from the old
+> `examples/issue-0030.sx` placeholder during the test-layout migration. Repro:
+> `issues/0030-extern-global-declarations.sx` (currently a parse error — the
+> syntax doesn't exist yet).
+
+## Symptom / request
+
+Support an `extern G : T;` top-level form so a global **defined** in one sx
+source file can be **referenced** from another without threading it through
+parameters — mirroring how `#foreign` function declarations work (declared in one
+place, defined elsewhere, resolved at link time).
+
+```sx
+// game/main.sx
+g_metal_gpu : *MetalGPU = null;
+
+// game/chess/pieces.sx
+extern g_metal_gpu : *MetalGPU;          // ← parse error today
+
+load :: (self: *ChessPieces, path: [:0]u8) {
+    inline if OS == .ios {
+        tex := g_metal_gpu.create_texture(w, h, .rgba8, xx pixels);
+    }
+}
+```
+
+Today `pieces.load` takes `has_gpu: bool, gpu: GPU` params and `main.sx` threads
+them through; cross-file `extern` globals would drop that ceremony. Distinct from
+the existing `name : T #foreign;` form (an *external C* data symbol from
+libsystem etc. — see `examples/1205-ffi-foreign-global.sx`); this request is for
+sx-defined globals shared across sx modules.
+
+## Reproduction
+
+`issues/0030-extern-global-declarations.sx`:
+
+```sx
+#import "modules/std.sx";
+extern g_x : *void;          // want: a reference to a global defined elsewhere
+main :: () -> s32 { 0; }
+```
+
+`./zig-out/bin/sx run …` → `error: expected '::', ':=', or ':' after identifier`
+(the `extern` keyword/form is unparsed).
+
+## Implementation sketch
+
+- **parser** — surface syntax for `extern G : T;`. Must not clash with `G :: T;`
+  (type alias), `G : T = ---;` (uninitialized global), `G : T;` (typed global).
+  Reject `extern G : T = expr;` (an extern can't carry an initializer).
+- **src/ir/lower.zig** — record an extern-global stub that resolves at
+  module-link time.
+- **src/ir/emit_llvm.zig** — emit an `external` LLVM global (no storage, just a
+  reference). Globals already have first-class IR addresses; this adds an
+  "extern" flag meaning "emit a reference, not storage."
+
+## Caveat
+
+Encourages process-global state. Steer callers toward explicit parameter passing
+where reasonable; reserve for genuine process singletons (active GPU, active
+platform) where threading through every call site is more noise than signal.

issues/0030-extern-global-declarations.sx

@@ -0,0 +1,14 @@
+// Repro for issue 0030 (OPEN feature request): cross-file sx `extern` globals.
+// Want: `extern G : T;` declares a reference to a global defined in another sx
+// file (resolved at link time), mirroring `#foreign` functions. Today this is a
+// parse error — the form doesn't exist. Distinct from `name : T #foreign;`
+// (an external C data symbol; see examples/1205-ffi-foreign-global.sx).
+//
+// Expected (once implemented): parses; `g_x` resolves to a global defined
+// elsewhere. Actual: error "expected '::', ':=', or ':' after identifier".
+
+#import "modules/std.sx";
+
+extern g_x : *void;
+
+main :: () -> s32 { 0; }