Add --version flag to install.sh to install a specific GitHub release

[Copilot]

install.sh always installs the latest release. Add a --version flag so users can pin to any published GitHub release.

Changes

• install.sh: New --version <v> / --version=<v> flag (leading v optional). When set, the script queries releases/tags/v{version} instead of /latest and surfaces a clear error if the tag does not exist. Arg parsing converted from a for arg loop to a while loop so flags can take values and be combined in any order.
• docs/guides/quick-start.md and docs/zh-hans/guides/quick-start.md: Document the new flag in EN and zh-Hans.

Usage

# Latest (unchanged)
curl -sSL https://raw.githubusercontent.com/version-fox/vfox/main/install.sh | bash

# Specific version
curl -sSL https://raw.githubusercontent.com/version-fox/vfox/main/install.sh | bash -s -- --version 0.5.6

# Combined with --user
curl -sSL https://raw.githubusercontent.com/version-fox/vfox/main/install.sh | bash -s -- --user --version v0.5.6

[bytemain]

@aooohan 以前用的旧版本的 vfox 做 CI 里安装 node 的基建，最近发现更新新版 1.0.10 之后 CI 挂了，没太研究是怎么挂的，先把 CI 能力恢复一下

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 24.09%. Comparing base (9522202) to head (f3518a7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #659      +/-   ##
==========================================
- Coverage   25.03%   24.09%   -0.95%     
==========================================
  Files          82       82              
  Lines        5667     7084    +1417     
==========================================
+ Hits         1419     1707     +288     
- Misses       4072     5201    +1129     
  Partials      176      176              

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[Copilot]

Pull request overview

Adds support for installing a pinned vfox GitHub Release via install.sh, and documents the new capability in the Quick Start guides.

Changes:

• Extend install.sh argument parsing to support --version <v> / --version=<v> (leading v optional).
• Fetch release metadata from releases/tags/v{version} when --version is provided (otherwise use /latest).
• Document --version usage in EN and zh-Hans quick start guides.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
install.sh	Adds --version flag parsing and tag-based GitHub release lookup.
docs/guides/quick-start.md	Documents installing a specific version via --version.
docs/zh-hans/guides/quick-start.md	Same documentation update in zh-Hans.

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[Copilot]

--version only checks whether $2 is empty. If the next token is another flag (e.g. --version --user), this will incorrectly treat --user as the version and proceed with a bad API request. Consider treating a missing value as either $2 being empty or $2 starting with -, and error out in that case.