agents/peggy: surface schedules over daemon, Telegram, and dashboard

[erain]

Goal

Surface Peggy's scheduled runs (shipped in #273 / PR #279) over the
daemon protocol, Telegram, and the dashboard, so schedules can be
managed and observed without local CLI access to the daemon host.

Scope

• glue connect --schedules (and --schedules-json) to list schedules
  from a running daemon; add/remove over the daemon protocol.
• Telegram daemon command to list schedules (/schedules) for
  allowlisted chats.
• Dashboard section listing schedules and their next/last run + last
  error.

Out of scope

• Deferred-approval-over-Telegram for unattended side effects (separate
  follow-up if wanted).
• Cron-expression cadence (current: --every interval and --at one-shot).

Implementation notes

The scheduling core, persistence, per-schedule tier, and peggy schedule/schedules CLI already exist in agents/peggy
(schedule.go, schedule_store.go, scheduler.go). This issue is the
remote/observability surface over that core, mirroring how memories and
sessions are exposed through the daemon, Telegram, and dashboard.

Docs update required

• agents/peggy/README.md (daemon, Telegram, dashboard sections).
• agents/peggy/CHANGELOG.md.

Verification commands

go build ./...
go vet ./...
go test ./agents/peggy/... ./daemon/

Acceptance criteria

• A schedule can be listed from a running daemon via glue connect.
• Telegram lists schedules for allowlisted chats.
• The dashboard shows schedules with next/last run and last error.
• Build, vet, and the listed package tests are green.