Feature: version constraints for enabledPlugins in project settings

Feature Request

Support semver version constraints in enabledPlugins to allow project maintainers to control which plugin versions are loaded.

Proposed Syntax

{
  "enabledPlugins": {
    "my-plugin@my-marketplace": ["^2.0.0"]
  }
}

The JSON schema already accepts an array of strings for enabledPlugins values and describes it as supporting "extended format with version constraints," but this is not currently implemented.

Why: Security

When a project's .claude/settings.json uses extraKnownMarketplaces + enabledPlugins to distribute plugins to a team, there is no way to guard against breaking or malicious changes in a plugin update. A compromised or buggy plugin version would immediately propagate to every developer on the team.

With version constraints, project maintainers can:

• Pin to a known-good major version (^2.0.0) — prevents untested major bumps from reaching developers
• Pin to an exact version (=2.0.0) — maximum control for security-sensitive environments
• Set a minimum version (>=2.1.0) — ensure a security fix is picked up by all team members

This is especially important for large teams (100+ developers) where plugins include hooks that execute shell commands. A version constraint in the checked-in project settings acts as a gate, requiring a deliberate commit to upgrade.

Current Workaround

None. The only option is true/false, which always installs whatever version the marketplace provides.