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/0016-basic-while.sx

@@ -0,0 +1,50 @@
+#import "modules/std.sx";
+
+sumOf10 :: () -> s32 {
+    i:= 1;
+    s:=0;
+    while i <= 10 {
+        s+=i;
+        i+=1;
+    }
+    s;
+}
+
+someSum :: #run sumOf10();
+
+main :: () {
+    // Basic while loop: count to 5
+    i := 0;
+    while i < 5 {
+        i += 1;
+    }
+    print("count: {}\n", i);
+
+    // While with break
+    x := 1;
+    while x < 100 {
+        if x == 12 {
+            break;
+        }
+        x += 1;
+    }
+    print("break at: {}\n", x);
+
+    // While with continue: sum odd numbers 1-9
+    sum := 0;
+    j := 0;
+    while j < 10 {
+        j += 1;
+        // Skip even numbers
+        if j == 2 { continue; }
+        if j == 4 { continue; }
+        if j == 6 { continue; }
+        if j == 8 { continue; }
+        if j == 10 { continue; }
+        sum += j;
+    }
+    print("sum of odd 1-9: {}\n", sum);
+
+    print("sum {}", someSum);
+    
+}