ci(core-ref): pin to the Teams cutover, where 1.6.0 reached main

The two mechanical lines the phase owed. template/module.json already declares
^1.6.0; this is the sha that makes checkCoreApi agree with it, which it could
not do until the cutover landed - the check is an equality against a core on
main, and 1.6.0 had only ever been on edge.

The `why` block records what the check bought this time rather than just what it
is for. Writing the chapters against 1.6.0 is what found that core's inverted
slot fills named three of module-uo's slots literally, so the direction worked
for that one module and silently did nothing for any other game. A book written
for an audience outside this org is exactly the instrument that finds that, and
it was fixed in core before this pin moved.

Also: the pin skipped the Teams `edge` entirely. The kit is written against what
shipped, never against what is in flight.

Co-Authored-By: Claude <noreply@anthropic.com>

ci/core-ref.json

@@ -1,29 +1,34 @@
 {
   "repo": "https://gitea.whitlocktech.com/RunicGateway/website.git",
   "branch": "main",
-  "ref": "4ad8b2bb0ede2747622075dcfa4cb1fe460f91ca",
+  "ref": "963d734dcc09580a7d8bb676370b4faf9b8727b2",
   "why": [
     "The core this kit is written against, pinned to a commit rather than a branch.",
-    "This one is the MODULE_API_VERSION 1.5.0 bump, which is the version",
+    "This one is the Teams cutover, the commit MODULE_API_VERSION 1.6.0 reached",
-    "template/module.json declares. It moved here from the 1.4.0 bump because",
+    "`main` on, and 1.6.0 is what template/module.json declares. It moved here from",
-    "the kit's acceptance run found PublicLayout had no way to give a module",
+    "the 1.5.0 bump because Teams expanded the contract the book teaches: the",
-    "page the site's body wrapper, and core grew a `shell` prop for it - so the",
+    "template now registers a Team provider and declares slots for core to fill,",
-    "template now uses a member that only exists at this ref and later.",
+    "and both are members that exist only at this ref and later.",
     "",
     "Moving this pin is the moment someone re-reads the chapters: CI asserts the",
     "version template/module.json declares still equals this core's",
     "MODULE_API_VERSION, so a contract bump turns this repo red on purpose",
     "(MODULE_SYSTEM.md 2.11.1 d2, 2.10).",
     "",
-    "The branch said `edge` until 2026-08-12, when the module system cut over",
+    "That mechanism earned its keep this time. Writing the chapters against 1.6.0",
-    "and that branch was deleted (MODULE_SYSTEM.md 2.9). The SHA DID NOT MOVE:",
+    "found that core's inverted-slot fills named three of module-uo's slots",
-    "the pinned commit is an ancestor of `main`, so this is a label correction",
+    "literally, so the direction worked for that one module and silently did",
-    "and not a re-pin - the contract is still 1.5.0 and no chapter changed.",
+    "nothing for any other game - an empty page with nothing logged. That is the",
-    "Nothing in CI reads this field; it clones the repo and checks out the sha,",
+    "exact class of thing a book written for an audience outside this org is meant",
-    "which is why the cutover could not break the build and why a wrong label",
+    "to catch, and it was fixed in core before this pin moved.",
-    "here would have sat unnoticed. It is for the person deciding whether a",
+    "",
-    "newer core is worth re-reading the book for, and a branch that no longer",
+    "The branch said `edge` until 2026-08-12, when the module system cut over and",
-    "exists tells them nothing.",
+    "that branch was deleted (MODULE_SYSTEM.md 2.9). Teams cut a second `edge` and",
+    "this pin skipped it entirely: the kit is written against what shipped, never",
+    "against what is in flight. Nothing in CI reads the branch field - it clones",
+    "the repo and checks out the sha - which is why a wrong label here would sit",
+    "unnoticed. It is for the person deciding whether a newer core is worth",
+    "re-reading the book for.",
     "",
     "Same convention as Module-uo's ci/core-ref.json, deliberately - one file, one",
     "sha, reviewable in a diff."