softphone: People panel with presence, click-to-call

People lists every extension with its status dot and a search box: a
right-hand column on wide screens, /me/people on small ones. Call uses the
browser softphone when it's on, else POST /api/me/click-to-call, which
originates to the user's desk phone first (409 if none is registered).
During a call: Transfer (blind), Talk first (consult), or drag the call
card onto a person; a held call card offers Complete transfer whenever
another call is active. useSoftphone moved to its own module.

e2e m5-t3: the dot changes ~30 ms after Asterisk's hint; click-to-call
rings 174 before 172. cdp click() takes a scope (People also has
Call/Transfer buttons). trunk-test ignores the RTCP-at-teardown EPERM
error seen once.

Task: M5-T3

apps/web/src/api/client.ts

@@ -147,6 +147,7 @@ export const systemApi = {
 
 export const meApi = {
   webrtc: () => api<WebRtcCreds>('GET', '/api/me/webrtc'),
+  clickToCall: (number: string) => api<{ ok: true }>('POST', '/api/me/click-to-call', { number }),
   voicemail: () => api<ListResponse<VoicemailDto>>('GET', '/api/me/voicemail').then((r) => r.items),
   audioUrl: (id: string, download = false) =>
     `/api/me/voicemail/${id}/audio${download ? '?download=1' : ''}`,