paging: paging groups, *80 intercom, auto-answer headers

/api/paging-groups CRUD (members as memberIds). The generator renders
sp-page-{id} per 03 §6.11 (desk phones only, auto-answer headers via
sp-sub-autoanswer) plus the number in sp-local-numbers. Added the `s`
option so phones already on a call aren't paged, which also keeps a
pager who is a member from being paged themselves. A group with no
members just hangs up.

*80<ext> intercom checks the target first: digits only and an endpoint
in sp-from-ext, else ss-noservice (the spec's one-liner passed
${EXTEN:3} straight into Page()). Both written back into 03.

Web: Paging page (list, drawer form with member checkboxes). Golden
case paging. e2e m8-t4 with baresip phones that honor the headers
(sip_autoanswer): an ordinary call rings, a page is answered by itself
and muted, the busy pager is skipped, *80 is two-way, *80999 refused.
The check on a real Yealink/Grandstream stays open (09).

Task: M8-T4

apps/api/src/generator/golden-case.ts

@@ -20,6 +20,7 @@ export function loadCase(name: string): Snapshot {
     ringGroups?: Partial<Snapshot['ringGroups'][number]>[];
     queues?: Partial<Snapshot['queues'][number]>[];
     conferences?: Partial<Snapshot['conferences'][number]>[];
+    pagingGroups?: Partial<Snapshot['pagingGroups'][number]>[];
     ivrs?: Partial<Snapshot['ivrs'][number]>[];
     timeConditions?: Partial<Snapshot['timeConditions'][number]>[];
     holidays?: Snapshot['holidays'];
@@ -115,6 +116,14 @@ export function loadCase(name: string): Snapshot {
       id: c.id!,
       number: c.number!,
     })),
+    pagingGroups: (raw.pagingGroups ?? []).map((g, i) => ({
+      name: `Paging ${i + 1}`,
+      duplex: false,
+      members: [],
+      ...g,
+      id: g.id!,
+      number: g.number!,
+    })),
     routes: (raw.routes ?? []).map((r, i) => ({
       name: `Route ${i + 1}`,
       position: i,