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/0205-generics-generic-method-dot-call.sx

@@ -0,0 +1,28 @@
+// Dot-call dispatch for generic struct methods.
+//
+// Covers three shapes:
+//   1. non-generic method:                h.plain()
+//   2. generic method, explicit type arg: h.sized(s32)
+//   3. generic method, inferred from val: h.taking(99)
+
+#import "modules/std.sx";
+
+Holder :: struct {
+    n: s64;
+
+    plain :: (self: *Holder) -> s64 { self.n; }
+    sized :: (self: *Holder, $T: Type) -> s64 { size_of(T); }
+    taking :: (self: *Holder, $T: Type, v: T) -> T { v; }
+}
+
+main :: () -> s32 {
+    h : *Holder = xx malloc(size_of(Holder));
+    h.n = 7;
+
+    print("plain: {}\n", h.plain());
+    print("sized s32: {}\n", h.sized(s32));
+    print("sized s64: {}\n", h.sized(s64));
+    print("taking explicit: {}\n", h.taking(s32, 42));
+    print("taking inferred: {}\n", h.taking(99));
+    0;
+}