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/1014-errors-failable-or.sx

@@ -0,0 +1,25 @@
+// Failable `or` value-terminator (ERR step E2.4a). `lhs or value` where `lhs`
+// is a value-carrying failable (`-> (T, !E)`): on success the result is the
+// LHS value; on failure the LHS error is discarded and the result is the
+// terminator value. The whole expression is non-failable (type T). The chain
+// form (`try a or try b`) needs fallback-target routing and lands in E2.4b.
+// Rejections: `examples/232-failable-or-reject.sx`.
+
+#import "modules/std.sx";
+
+E :: error { Bad, Empty }
+
+parse :: (n: s32) -> (s32, !E) {
+    if n < 0  { raise error.Bad; }
+    if n == 0 { raise error.Empty; }
+    return n * 2;
+}
+
+main :: () -> s32 {
+    a := parse(5) or 0;        // success → 10
+    b := parse(-1) or 99;      // Bad     → 99 (terminator)
+    c := parse(0) or 7;        // Empty   → 7  (terminator)
+    r := a + b + c;            // 10 + 99 + 7 = 116
+    print("or result: {}\n", r);
+    return r;
+}