Follow terdut-server into teams: switch team, per-team schedule

terdut-server v0.12 made everything team-scoped and v0.20 is what this
client now targets. Against it the old client was wrong in three ways:
the schedule moved to /api/teams/{id}/schedule, GET /api/schedule/current
became a list with one entry per team, and users, incidents, alerts and
schedule entries all grew fields the client ignored.

T steps through all teams and then each of yours. The header names what
is showing, and incident and alert rows gain a Team column when more than
one team can appear. team: in config.yaml picks the team to start on, by
name or id; an unknown one is reported and falls back to all teams.

The schedule is one team's rota, so it shows the active team, or with
all teams showing the first one you own. Writes need an owner or an
administrator, and the picker offers only the team's members, since the
server answers 404 for anybody else. Both are checked up front and the
reason goes in the status bar, rather than surfacing as a 403 after the
user has picked somebody. Stats are not team-scoped by the server and
stay that way here.

Users shows an admin/disabled Flags column. Creating and deleting users
is administrators only, and topic, keys and password work on your own
row or on anyone's for an administrator; the server enforces the same
rule, this only explains it before the round trip.

The server has no version endpoint, so an older one is recognised by
GET /api/teams answering 404, and the TUI says it needs v0.20 or later.
Connecting now also loads /api/teams and /api/me with the key, which
means a wrong key fails on start instead of on the first list; /healthz
does not check it. There is no fallback to the pre-team paths.

Rebuilding a table whose column count changes under loaded rows panicked
inside bubbles, because it re-renders the old rows on SetColumns. The
rows are now cleared first and the cursor put back, so a refresh still
does not jump to the top.

Escalation ladders, invites, integrations and the admin settings are
left to the server's web UI. Checked against a real v0.20.1 server with
two teams, an administrator and a plain member.

Breaking: requires terdut-server v0.20.0 or later. Use terdut-tui v0.9.x
with servers before v0.12.

main.go

@@ -46,7 +46,7 @@ func main() {
 	}
 
 	client := api.NewClient(cfg.ServerURL, cfg.APIKey)
-	model := tui.NewModel(client, cfg.ServerURL, cfg.RefreshInterval, th)
+	model := tui.NewModel(client, cfg.ServerURL, cfg.RefreshInterval, th).WithDefaultTeam(cfg.Team)
 
 	p := tea.NewProgram(model, tea.WithAltScreen())
 	if _, err := p.Run(); err != nil {