feat(annotations): add dashboard/notebook annotations commands

[platinummonkey]

Summary

Adds the Annotations API v2 (SDK #1631) to pup. Annotations attach to a page — dashboard:<id> or notebook:<id> — and mark moments/regions in time on dashboard and notebook widgets, so the commands are nested under both pup dashboards annotations and pup notebooks annotations (sharing one module), rather than a top-level domain.

Changes

• src/commands/annotations.rs — new module: list, get_page, create, update, delete
• src/commands/mod.rs — register the module
• src/client.rs — register the 5 annotation ops as unstable (UNSTABLE_OPS 162 → 167)
• src/main.rs — Annotations subcommand added to both DashboardActions and NotebookActions, dispatched through a shared run_annotations helper
• docs/COMMANDS.md — documented under the dashboards and notebooks rows

New commands

pup dashboards annotations list --page-id dashboard:<id> --start <ts> --end <ts>
pup dashboards annotations create --file body.json
pup notebooks annotations list --page-id notebook:<id> --start <ts> --end <ts>
pup notebooks annotations get-page --page-id notebook:<id> --start <ts> --end <ts>
# update/delete also available under both

Testing

• list / get-page / create / update / delete + error and bad-file paths
• Validated locally against the pinned SDK rev: cargo test green, cargo fmt --check clean, cargo clippy clean (no warnings in pup code). Top-level command alphabetical-order check passes (no new top-level command added).

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