feat(plugin): support batch updating all installed plugins

[ByteYue]

Description

Adds the ability to update all installed plugins at once via opencli plugin update --all.

• Refactors opencli plugin update [name] to make the name optional if --all is provided.
• Implements updateAllPlugins() which iterates over all installed plugins.
• Collects success/failure states so that a single plugin update failure (e.g., network timeout) does not interrupt the entire batch process.
• Displays a summary report of successful and failed updates at the end.

[jackwener]

Deep review completed. I kept the batch-update feature, removed the unrelated E2E scope from the effective patch, simplified the update-all implementation, added targeted plugin tests, and synced the plugin docs/README examples.

[jackwener]

Thanks for the contribution. I kept the core \ feature, narrowed the effective scope to plugin management only, added targeted regression coverage, and synced the plugin docs so the command is discoverable.