fix: handle 'latest' version string in plugin semver check

[AmanKRoy]

Problem

When a plugin is specified without a version (e.g., my-plugin instead of my-plugin@1.0.0), opencode defaults the version to the string "latest". The Npm.outdated() function then calls semver.lt("latest", ...), which throws because "latest" is not a valid SemVer string.

This matches issue #12143.

Fix

Added an early return in Npm.outdated() that skips the version check when cachedVersion === "latest".

Testing

• Verified that plugins without a version no longer cause crashes
• Verified that plugins with explicit versions still update correctly

Fixes #12143

[github-actions]

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential duplicate PR found:

• PR fix: handle non-semver cached versions in plugin installer #12265: fix: handle non-semver cached versions in plugin installer
  • fix: handle non-semver cached versions in plugin installer #12265

Why it's related: This PR addresses the same issue of handling non-SemVer version strings (like 'latest') in the plugin installer's version checking logic. Both PRs appear to fix the same root cause - preventing crashes when plugin versions don't conform to valid SemVer format.

[AmanKRoy]

Duplicate of PR #12265 which addresses the same issue (#12143). Closing in favor of the existing PR.