Phase 9: application services and admin completion

Implements PLAN.md Phase 9. internal/appservice reads registration files
(appservice.config_files), matches namespaces the way Synapse does
(anchored at the start), and delivers events to each service as
transactions read from the roomserver's event stream at a cursor kept in
appservice_state. A transaction in flight is recorded, so after a restart
it is resent under the same ID; failures back off from 2s to 5m, and a
successful ping cuts the backoff short.

In the Client-Server API an as_token acts as the service's sender or, with
?user_id=, as any existing user in its namespace. Services register and
log in their users with m.login.application_service; exclusive user and
alias namespaces are refused to everybody else with M_EXCLUSIVE. Unknown
aliases and users in a namespace are asked of the service first. The
ping endpoint reports M_URL_NOT_SET, M_BAD_STATUS, M_CONNECTION_FAILED
and M_CONNECTION_TIMEOUT. Services' own requests, and their users' when
rate_limited is false, skip the rate limiter.

Users can change their password (POST /account/password) and deactivate
their account (POST /account/deactivate), both behind the password.
Deactivation revokes tokens, deletes devices, optionally erases the
profile and leaves every room through a new userapi.AccountObserver.

The admin API is complete: user detail, the admin flag, deactivation and
reactivation, password resets, devices, media quotas
(media.max_user_storage_bytes plus per-user overrides), registration
tokens with use limits and expiry (registration.require_token), server
notices (internal/servernotices, server_notices.*), an editor for the
federation allow/deny lists persisted in server_settings, a delivery view
of the application services, and an audit log of every change.

Migration 0011 adds the registration token, server notice room, media
quota, audit log and appservice cursor tables. Policy lists are now
returned sorted. The Complement entrypoint loads the registrations
Complement mounts in /complement/appservice.

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

server/internal/adminapi/notices.go

@@ -0,0 +1,62 @@
+package adminapi
+
+import (
+	"errors"
+	"net/http"
+
+	"github.com/dariuszjaniak/warp/server/internal/httputil"
+	"github.com/dariuszjaniak/warp/server/internal/servernotices"
+	"github.com/dariuszjaniak/warp/server/internal/userapi"
+)
+
+// serverNoticeRequest is the POST /server_notices body.
+type serverNoticeRequest struct {
+	UserID string `json:"user_id"`
+
+	// Content is an m.room.message content. A body is required; a missing
+	// msgtype becomes m.text.
+	Content map[string]any `json:"content"`
+}
+
+// handlePostServerNotice implements POST /_warp/admin/v1/server_notices:
+// send a message from the server to one of its users.
+//
+// The notice goes into the user's server notice room, which is made the
+// first time and which the user is invited back to if they left it. The
+// user does not have to be online or to accept anything first: the
+// invite and the message wait for them.
+func (a *AdminAPI) handlePostServerNotice(w http.ResponseWriter, r *http.Request, auth userapi.Authenticated) error {
+	if a.notices == nil {
+		return httputil.NewError(http.StatusConflict, httputil.ErrCodeForbidden,
+			"Server notices are not configured (server_notices.enabled is false, or the server has no signing key)")
+	}
+	var req serverNoticeRequest
+	if err := httputil.DecodeJSON(w, r, &req); err != nil {
+		return err
+	}
+	if req.UserID == "" {
+		return httputil.MissingParam("user_id is required")
+	}
+	if body, _ := req.Content["body"].(string); body == "" {
+		return httputil.MissingParam("content.body is required")
+	}
+	localpart, err := a.users.ParseLocalUserID(req.UserID)
+	if err != nil {
+		return httputil.InvalidParam("%s is not a user of this server", req.UserID)
+	}
+
+	roomID, eventID, err := a.notices.Send(r.Context(), localpart, req.Content)
+	switch {
+	case errors.Is(err, servernotices.ErrNoSuchUser):
+		return httputil.NotFound("No such user")
+	case errors.Is(err, servernotices.ErrDeactivated):
+		return httputil.Forbidden("%s is deactivated", req.UserID)
+	case err != nil:
+		return roomError(err)
+	}
+	a.audit(r.Context(), auth, auditServerNotice, a.users.UserID(localpart), map[string]any{
+		"room_id": roomID, "event_id": eventID,
+	})
+	httputil.WriteJSON(w, http.StatusOK, map[string]string{"room_id": roomID, "event_id": eventID})
+	return nil
+}