docs(getting-started): avoid cloning a non-existent v0.1.0 tag

[starliu1996]

Summary

The shortest Getting Started path currently asks users to clone the v0.1.0 tag, but the public repository currently has no v0.1.0 tag or GitHub Release.

Actual behavior

Running:

git clone --branch v0.1.0 --depth 1 https://github.com/tiammomo/ModelPort.git

fails with:

warning: Could not find remote branch v0.1.0 to clone.
fatal: Remote branch v0.1.0 not found in upstream origin

The source-build quick start in README.md uses the default branch, while docs/GETTING_STARTED.md requires a tag that has not been published.

Expected behavior

The source-build Getting Started path should clone the current default branch. The separate release-image path can remain gated on the future v0.1.0 tag and GHCR images.

Steps to reproduce

1. Check the public repository Tags and Releases pages; neither currently contains v0.1.0.
2. Run git clone --branch v0.1.0 --depth 1 https://github.com/tiammomo/ModelPort.git.
3. Observe that Git reports the remote branch or tag v0.1.0 was not found.

Environment

• ModelPort main at fa2b510
• Linux/WSL2 x86_64
• Git 2.43.0
• Checked 2026-08-31

Proposed acceptance criteria

• Update docs/GETTING_STARTED.md so the source-build clone command succeeds against the current default branch.
• Keep the release instructions explicit that the v0.1.0 tag and release images must exist before using that path.
• Verify the documented clone command and relative documentation links.
• Keep English and Chinese entry pages aligned if any shared command or status statement changes.

This is a documentation-only change; it does not alter APIs, configuration, dependencies, or deployment behavior.