feat(rust): a Steam account linked on the site is a Rust link (D392, D396)

Registers core's MODULE_API 1.17.0 identity hooks (coreApi ^1.17.0):
onIdentityLinking refuses a Steam id that is another website account's Rust
link (D396); onIdentityLinked writes the Rust link with the PRIMARY KEY as the
race guard, reconciles Teams and raises the linked notice, as /link does.
Unlinking Steam leaves the Rust link (D393); the Rust account page says so.

ci/core-ref.json still pins the 1.15.0 core and must move to the website
branch head carrying 1.17.0 before CI can pass.

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

server/test/entry.test.js

@@ -85,6 +85,13 @@ test('registers both lifecycle hooks', () => {
   assert.strictEqual(typeof api.record.hooks.onShutdown, 'function')
 })
 
+test('registers both identity hooks, so a Steam sign-in link is a Rust link (D392, D396)', () => {
+  const { api } = register()
+  const links = require('../model/links/links.model')
+  assert.strictEqual(api.record.hooks.onIdentityLinking, links.checkSteamSignin)
+  assert.strictEqual(api.record.hooks.onIdentityLinked, links.linkFromSteamSignin)
+})
+
 test('the manifest declares what the loader requires', () => {
   assert.match(manifest.id, /^[a-z][a-z0-9-]{1,31}$/)
   assert.match(manifest.version, /^\d+\.\d+\.\d+/)