## Summary
- Adds a new `semver` Lua module that vfox plugins can use for semantic
version comparison and sorting
- Eliminates the need for each plugin to implement their own version
sorting logic

## API
- `semver.compare(v1, v2)` - Returns -1, 0, or 1
- `semver.parse(version)` - Returns table of numeric parts
- `semver.sort(versions)` - Sorts string array ascending
- `semver.sort_by(items, field)` - Sorts table array by version field

## Example Usage
```lua
local semver = require("semver")

-- Method 1: Use in custom sort
table.sort(result, function(a, b)
    return semver.compare(a.version, b.version) < 0
end)

-- Method 2: Use sort_by helper
result = semver.sort_by(result, "version")
```

## Test Plan
- [x] Unit tests for `parse_version`, `compare_versions`
- [x] Lua integration test

## Related
- vfox-postgres fix:
mise-plugins/vfox-postgres#2

🤖 Generated with [Claude Code](https://claude.ai/code)

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Adds a built-in `semver` Lua module and integrates it into the plugin
runtime.
> 
> - New `lua_mod/semver.rs` exports `compare`, `parse`, `sort`, and
`sort_by` for semantic version handling; includes unit and Lua
integration tests
> - Registers `semver` in `lua_mod/mod.rs` and loads it in `plugin.rs`
so `require("semver")` is available to plugins
> - Updates `docs/plugin-lua-modules.md` with `semver` usage and
examples
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
e97711a. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>