[Feature]: Pre-install himalaya and other commonly used CLI tools in Docker image

## Summary

Pre-install `himalaya` and other commonly used CLI tools in the official Docker image, so users don't need to reinstall them every time they rebuild containers.

## Component(s) Affected

- [x] Core / Backend (app, agents, config, providers, utils, local_models)
- [ ] Console (frontend web UI)
- [ ] Channels (DingTalk, Feishu, QQ, Discord, iMessage, etc.)
- [ ] Skills
- [ ] CLI
- [ ] Documentation (website)
- [ ] Tests
- [ ] CI/CD
- [x] Scripts / Deploy

## Problem / Motivation

Currently, when using the official Docker image, users need to manually install CLI tools like `himalaya` every time the container is rebuilt. This creates a poor user experience because:

1. Tools like `himalaya` are referenced in the Skills documentation but not available out-of-the-box
2. Users have to reinstall dependencies every time, which is time-consuming
3. This makes it difficult to use email-related Skills seamlessly in containerized environments

## Proposed Solution

Include `himalaya` and other frequently used CLI tools in the Docker image by default. Consider:

1. Adding `himalaya` to the Dockerfile
2. Optionally including other commonly used tools referenced in Skills (e.g., other CLI utilities)
3. Documenting what tools are pre-installed

## Alternatives Considered

- Users can create their own custom Docker images, but this requires extra effort
- Users can mount a volume with pre-installed tools, but this is complex

## Additional Context

The `himalaya` skill is documented in the Skills folder, suggesting it's an intended feature. Pre-installing it would improve the out-of-the-box experience for Docker users.

## Willing to Contribute

- [ ] I am willing to open a PR for this feature (after discussion).