docs(kit): pin core 1.17.0; teach 1.13.0 to 1.17.0 and one module per site

The pin moves from 0a37a44 (1.12.0) to 6890a74 (1.17.0, website#220),
past 1.13.0 to 1.16.0, which reached main in the same cutover. The
chapters were read again for all five versions:

- Chapter 5: a lease's example, an option row's note, a param's
  duration (1.13.0) and multiple (1.14.0), a retry's retryAfterMs
  (1.15.0), a dry run's warnings (1.16.0), and a new section on
  templates (1.13.0). "What to build, in order" gains a template as
  step 8.
- Chapter 2: a new section on the identity-link hooks and
  ctx.identities.list (1.17.0). The call count is corrected to
  nineteen; it said twelve, which was already stale at 1.10.0.
- Two core changes in that cutover carried no version bump, and both are
  taught. Chapter 1 now says a site runs one game module and the loader
  refuses the others, since a reader copying the template onto a UO or
  Rust core is the one it surprises. Chapter 5 now covers a resource's
  `until`, which reconcile reads.

The template declares none of the new members, so nothing it does
changed meaning. template/module.json's coreApi becomes ^1.17.0 for the
equality check.

Checks run at the new pin:
- checkCoreApi, links, rename sites and chapter paths all pass, and so
  do the script tests (10 and 11).
- The template's imports, build, externals and swagger checks pass.
- Tests pass: server 82, client 20.
- The template was loaded as `examplegame` into a real core of this code
  through core's own loader, and it registered. Loaded again beside
  module-uo, examplegame started and uo was refused with the reason
  chapter 1 quotes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

ci/core-ref.json

@@ -1,10 +1,29 @@
 {
   "repo": "https://gitea.whitlocktech.com/RunicGateway/website.git",
   "branch": "main",
-  "ref": "0a37a44164ab107584b918e656651452b50bd4f3",
+  "ref": "6890a74c7c4ad5690509e8c163e477d7f7b399e7",
   "why": [
     "The core this kit is written against, pinned to a commit rather than a branch.",
     "",
+    "2026-10-23: moved from 0a37a44 (1.12.0) to 6890a74 (1.17.0, website#220,",
+    "the cutover that brought Steam sign-in and the Rust last fixes to `main`),",
+    "past 1.13.0 to 1.16.0, which reached `main` together on 2026-10-22. The",
+    "chapters were read again for all five versions:",
+    "- 1.13.0: templates (chapter 5 gains a section), a param's duration, a",
+    "  lease's example, an option row's note;",
+    "- 1.14.0: a param's multiple and max;",
+    "- 1.15.0: a retry's retryAfterMs;",
+    "- 1.16.0: a dry run's detail.warnings;",
+    "- 1.17.0: onIdentityLinking / onIdentityLinked and ctx.identities.list",
+    "  (chapter 2 gains a section, and its call count is corrected to nineteen).",
+    "Two core changes in the same cutover carried no version bump, and both are",
+    "taught: a site runs ONE game module, which the loader now enforces at boot",
+    "(chapter 1, the reader most likely to be surprised by it), and a resource's",
+    "`until` is read at reconcile (chapter 5). The template declares none of the",
+    "new members, so nothing it does changed meaning; module.json's coreApi",
+    "becomes ^1.17.0 for the equality check. The real core run was repeated at",
+    "this ref, with the template as the only module in the directory.",
+    "",
     "2026-10-06: moved from 655fbf3f (1.10.0) to 0a37a44 (1.12.0, website#210),",
     "past 1.11.0 (website#209), which this pin had skipped. Chapter 5 was read again",
     "for both versions and gained two paragraphs:",