feat(kit): the two shapes Teams added, taught and built

MODULE_API 1.6.0 expands the contract this book teaches against, so the book
owes two shapes and one correction. Chapter 2 gains both and the template grows
a working version of each, because a reader following a snippet has no way to
find out whether it runs.

ONE SENTENCE WAS WRONG. Chapter 2 said, of extension slots, "Only core may
declare a slot; a module may only fill one". 1.6.0 inverted exactly that: a
module declares a place on its OWN page and core fills it. That is not a stale
detail - a new game's module cannot implement Teams at all without the inverted
direction, so it is the shape the reader needs and did not have.

THE TWO SHAPES

- The inverted slot. A new "Slots go the other way too" section: why the
  direction has to invert (core owns the Team, not the word for one), the
  namespace rule, one slot per PLACE, the optional { core } naming which of
  core's three contributions goes there, and why asking for one core does not
  offer throws when almost everything else in that registry fails open.

- registerTeamProvider, in "Becoming the source of Teams". The first
  registration where core calls YOU and waits, which is where every rule in it
  comes from: the envelope, the ten-second budget, refusing as a normal answer,
  and the one mistake worth naming - answering with an empty list because the
  game is unreachable, which core reads as authoritative and acts on.
  projectRoster gets its own treatment because it is the exception that fails
  CLOSED. pageUrlTemplate is a footnote beside it, as intended.

WHAT THE TEMPLATE GREW

model/clans/ - the provider over two tables, with the guards that matter: an
unreachable game refuses rather than reporting no clans, an empty roster is
refused unless the game says the clan is empty (which is why the schema keeps a
member count the rows cannot supply), and the audience rule lives in one file
that both projectRoster and the module's own page consult, because a second copy
drifts in the direction that publishes what core is withholding.

Its own /clans routes, deliberately not /teams - core mounts that itself, and
the loader would refuse the collision. A clan list page and a clan page that
declares three slots for core.

12 provider tests and three registration tests, 47 server and 20 client in
total. The purge test finally proves something: two of the three tables are now
a parent and its child.

WHAT IT DOES NOT DO. Enumerate the contract. The kit teaches one path end to end
and links out; it has never mentioned three pre-Teams registrations and that is
the design, not a gap.

FOUND WHILE WRITING IT: core filled three literal uo.guild.* slot names, so the
inverted direction reached exactly one module and every other game's page came
up empty with nothing logged. Fixed in website#160 / Module-uo#15 / docs#165
before this chapter could teach it - which is what this phase is for.

The ci/core-ref.json pin moves in a later commit on this branch: checkCoreApi is
an equality against a core on main, and 1.6.0 does not reach main until the
cutover.

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

template/server/index.js

@@ -48,6 +48,8 @@ module.exports = function register(ctx, api) {
 
   /* eslint-disable global-require */
   const worldRouter = require('./router/public/world.router')
+  const clansRouter = require('./router/public/clans.router')
+  const clanProvider = require('./model/clans/clanProvider.model')
   const boot = require('./boot')
   /* eslint-enable global-require */
 
@@ -74,9 +76,33 @@ module.exports = function register(ctx, api) {
   // is exactly the one that would have gone wrong. Check the list before you
   // choose (§2.4, and MODULE_SYSTEM.md §2.7's own note about the probe).
   api.registerRoutes({
-    public: { '/world': worldRouter },
+    public: { '/world': worldRouter, '/clans': clansRouter },
   })
 
+  // ── Teams: this module is the authoritative source of them ───────────────
+  //
+  // A Team is a CORE entity — core owns the tables, the reconciler, the access
+  // rules, the forum and the activity feed. What core does not own is the word for
+  // one, because this game says clan and the next will say company. So core asks
+  // this module three questions and never reads its tables (MODULE_API 1.6.0).
+  //
+  // **This is the first registration where core calls YOU and waits**, which is
+  // what makes it unlike every other line in this file: the others hand core a
+  // router to mount or a row to draw. Two consequences worth carrying:
+  //
+  //   • **Registration is a claim, not a call.** Nothing in the provider runs
+  //     until core reconciles, which is after `onBoot` — which is what makes it
+  //     legal for every one of its methods to read the database while this
+  //     function may not (§2.2).
+  //   • **One provider per deployment.** Unlike every other registry this holds a
+  //     single value: two modules answering "what Teams exist" would produce two
+  //     disjoint sets under one table with no rule for merging them. A second
+  //     registration is a collision, reported against the module that holds it.
+  //
+  // The whole object is passed rather than picking its members out, so adding the
+  // optional ones is an edit to the provider and not to this file.
+  api.registerTeamProvider(clanProvider)
+
   // The lifecycle hooks (§2.5). `onBoot` runs after core's schema, after this
   // module's schema fragment, and BEFORE the HTTP listener binds — so a module
   // that must not serve traffic until it has warmed a cache gets that for free.
@@ -93,6 +119,6 @@ module.exports = function register(ctx, api) {
 
   log.info('registered', {
     version: require('../module.json').version,
-    routes: 'public:/world',
+    routes: 'public:/world,/clans',
   })
 }