go: after(d) timer stub + 13 pattern tests → runtime 40/40, Phase 5 closed [shapes-scheduler]

Acceptance bar hit (40 runtime, 497 total). Tests: timer ready,
select-with-timeout, fan-in (3 producers), worker queue, pipeline,
fan-out-then-fan-in, select source-order, fallback case, default,
producer-consumer, two-stage pipeline, channel-counter, after+default,
tick-collector.

Shape chiselled: timer collapses "after duration" into
"channel ready immediately" — select needs only ready? from each
case. Real time is when the flip happens, not what the protocol is.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/go/scoreboard.json

@@ -1,13 +1,13 @@
 {
   "language": "go",
-  "total_pass": 483,
-  "total": 483,
+  "total_pass": 497,
+  "total": 497,
   "suites": [
     {"name":"lex","pass":129,"total":129,"status":"ok"},
     {"name":"parse","pass":176,"total":176,"status":"ok"},
     {"name":"types","pass":72,"total":72,"status":"ok"},
     {"name":"eval","pass":80,"total":80,"status":"ok"},
-    {"name":"runtime","pass":26,"total":26,"status":"ok"},
+    {"name":"runtime","pass":40,"total":40,"status":"ok"},
     {"name":"stdlib","pass":0,"total":0,"status":"pending"},
     {"name":"e2e","pass":0,"total":0,"status":"pending"}
   ]