Group voice and video calls with MatrixRTC and LiveKit

Every call in the web client now goes through MatrixRTC with a LiveKit
SFU, the model Element Call and Element X use; the legacy 1:1 m.call.*
calls are gone. In a room of two the other person is rung and can answer
or decline; in a bigger room a banner offers to join the call. Calls show
a grid of participant tiles with mute, camera, screen sharing and leave,
and media is end-to-end encrypted in encrypted rooms.

Server:
- MSC4140 delayed events (send/state with a delay, plus the
  delayed_events list/restart/cancel/send API), stored and scheduled, so
  a member whose client drops off is taken out of the call.
- POST /user/{userId}/openid/request_token, which lk-jwt-service uses to
  hand out LiveKit tokens.
- org.matrix.msc4143.rtc_foci in /.well-known/matrix/client, configured
  under client_api.rtc.
- Room presets let members send call membership state.
- Migration 0014 for both SQL dialects.

Deploy: LiveKit and lk-jwt-service in compose (calls.yml) and the helm
chart. Docs: docs/calls.md, configuration and deployment.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/internal/clientapi/rooms.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"strings"
 
+	"github.com/dariuszjaniak/warp/server/internal/delayedevents"
 	"github.com/dariuszjaniak/warp/server/internal/httputil"
 	"github.com/dariuszjaniak/warp/server/internal/matrix/id"
 	"github.com/dariuszjaniak/warp/server/internal/roomserver"
@@ -155,10 +156,20 @@ func (c *ClientAPI) handleSendEvent(w http.ResponseWriter, r *http.Request, auth
 		return httputil.MissingParam("A transaction ID is required")
 	}
 
+	delay, delayed, err := c.delayRequested(r)
+	if err != nil {
+		return err
+	}
 	var content sendEventRequest
 	if err := httputil.DecodeJSON(w, r, &content); err != nil {
 		return err
 	}
+	if delayed {
+		return c.scheduleDelayed(w, r, delayedevents.ScheduleRequest{
+			UserID: auth.UserID, DeviceID: auth.DeviceID, RoomID: roomID,
+			Type: eventType, Content: content, Delay: delay,
+		})
+	}
 
 	eventID, err := c.rooms.SendEvent(r.Context(), roomserver.SendEventRequest{
 		RoomID:      roomID,
@@ -191,10 +202,20 @@ func (c *ClientAPI) handlePutState(w http.ResponseWriter, r *http.Request, auth
 	}
 	stateKey := r.PathValue("stateKey")
 
+	delay, delayed, err := c.delayRequested(r)
+	if err != nil {
+		return err
+	}
 	var content sendEventRequest
 	if err := httputil.DecodeJSON(w, r, &content); err != nil {
 		return err
 	}
+	if delayed {
+		return c.scheduleDelayed(w, r, delayedevents.ScheduleRequest{
+			UserID: auth.UserID, DeviceID: auth.DeviceID, RoomID: roomID,
+			Type: eventType, StateKey: &stateKey, Content: content, Delay: delay,
+		})
+	}
 
 	eventID, err := c.rooms.SendEvent(r.Context(), roomserver.SendEventRequest{
 		RoomID:   roomID,