ICloudProvider missing batch operations

**Severity:** Low
**Component:** Provider Interface
**Simulation:** SIM-L4-001
**Sprint:** 5

## Description
No batch operations in ICloudProvider makes bulk operations inefficient.

## Proposed Fix
Add batch_delete, batch_move, batch_metadata methods.

## Source
Imported from `.straymark/02-design/risk-analysis/BACKLOG-simulation-issues.md` on 2026-05-29.