test: migrate examples to XXXX-category-name layout + split expected streams

Rename all example tests/companions to the XXXX-category-test-name scheme
(per-category 100-blocks: basic 0010, types 0100, ... errors 1000,
diagnostics 1100, ffi 1200, ffi-objc 1300, ffi-jni 1400, vectors 1500,
platform 1600). Companions and dir/C fixtures move in lockstep with their
parent test; #import/#source/#include paths rewritten to match.

Expected output now lives in examples/expected/ (a sibling dir of the
tests) split into three streams per the new convention:
  <name>.exit / <name>.stdout / <name>.stderr  (+ optional <name>.ir)

run_examples.sh rewritten: scans examples/ and issues/ for an
expected/<name>.exit marker, captures stdout and stderr separately (no
more 2>&1), compares each stream + exit + optional IR snapshot.

Behavior validated unchanged: every renamed test reproduces its prior
merged output + exit (diffs limited to file paths/basenames embedded in
diagnostics + traces, which correctly reflect the new names). Suite:
292 passed, 0 failed. 50-smoke.sx split + issue relocation + docs follow
in subsequent commits.

examples/1327-ffi-objc-call-01-parse.sx

@@ -0,0 +1,25 @@
+// Phase 1 step 1.0 (PLAN-FFI.md): xfail test for the `#objc_call`
+// parser. The shape is `#objc_call(ReturnT)(receiver, "selector:",
+// args...)` — return type in the first parens, then a normal call.
+// Today the parser rejects this; the snapshot captures the rejection.
+//
+// Phase 1.1 adds the parse rule and the snapshot updates to whatever
+// the next pipeline stage produces (sema / codegen can't lower the
+// intrinsic until later steps).
+//
+// Phase 1.3+ wires the lowering (selector interning + objc_msgSend
+// dispatch) and the test eventually runs cleanly against Foundation.
+
+#import "modules/std.sx";
+
+main :: () -> s32 {
+    // `#objc_call(void)` with a null receiver — never executed (this
+    // file's purpose is parser surface coverage). `inline if false`
+    // would suppress sema/codegen too, but for the parse-only step
+    // we want the AST to actually carry the node.
+    inline if false {
+        #objc_call(void)(null, "init");
+    }
+    print("parse-only ok\n");
+    0;
+}