fix: address final-review polish (docs + comments + test coverage)

- AGENTS.md bind-production code block: shows the slim default state
  (no @repo/core-events / @repo/core-realtime imports, BindProductionContext
  with no generic args) with a comment pointing to the scaffold workflow.
  The previous block showed a fully-wired post-scaffold state without
  signaling that none of those packages exist in main.
- bind-protocols.test.ts: top-of-file comment clarifies what these tests
  actually verify (protocol shapes have required methods) vs what the
  spec text might suggest (full assignability of optional packages'
  interfaces — that's verified by the e2e reconstruction tests, not here).
- core-package-generator.md: drops two stale "Until Phases 3-6 land"
  parentheticals — the phases shipped.
- config.test.ts: extends the choices assertion to cover all 4 names
  (realtime, events, trpc, ui).
- marketing-pages bind-* comments: reverse the inverted optional/required
  language. queue (IJobQueue) is from core-shared and always present;
  bus is the optional one (from @repo/core-events when scaffolded).

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

packages/marketing-pages/src/di/bind-production.ts

@@ -129,7 +129,8 @@ export function bindProductionMarketingPages(ctx: BindProductionContext): void {
 
   // <gen:event-handlers>
   // onAuthUserSignedUpHandler subscription — generated, edit the handler file (not this block) for behavior.
-  // queue is optional: guard so the handler is only bound when core-jobs is wired (Phase 3+).
+  // bus is optional: when @repo/core-events is not scaffolded, ctx.bus is undefined and the handler is not bound.
+  // queue (IJobQueue) is in core-shared and always provided; the inner if (queue) below is belt-and-suspenders.
   if (queue) {
     const wrappedAuthUserSignedUp = withSpan(
       tracer,