Mobile: restore Scheduled Tasks, multi-run, and Archive entry points

Background

The desktop sidebar header exposes three entry points: Scheduled Tasks, New multi-run, and Archive. The mobile app shell renders none of them, so phone users cannot open scheduled tasks, start a multi-run, or browse and restore archived sessions.

These entry points were reachable on phones until commit e103f3634 (2026-08-24, "refactor(layout): remove the legacy mobile layout"). That commit deleted the legacy mobile branch that rendered SessionSidebar in the left drawer, and the replacement mobile sessions shell never re-added them. The mobile list also filters archived sessions out entirely, so a session archived by swipe can never be viewed or restored on mobile.

The underlying components are UI-store-driven and shell-agnostic, so this is mobile chrome work rather than new features. Related: #3017 tracks the missing Scheduled Tasks entry; this issue extends the ask to multi-run and Archive and asks for all three to come back together.

Version

336e192 (main, OpenChamber 1.24.2, OpenCode 1.18.32)

Acceptance Criteria

Must

• The mobile sessions view has an entry point that opens the Scheduled Tasks dialog, and viewing or creating a scheduled task works there
• The mobile sessions view has an entry point that opens the multi-run launcher, and a multi-run can be started from it
• The mobile sessions view has an entry point that opens the Archive view
• Archived sessions can be viewed and restored to active from the mobile Archive view
• Opening any of these surfaces closes the mobile sessions drawer or sheet, consistent with existing mobile navigation behavior

Should

• The dialogs and Archive view respect mobile safe areas and small-viewport sizing
• Multi-run launch from mobile has touch-friendly agent and directory pickers

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Created with create-issue via glm-5.3-flash (32191b8)