[Bug]: Installing plugin with Opencode 1.3.8+ fails due to change in packge.json parsing #24

Description

When I install the plugin with a recent version of opencode (1.3.8+), it fails because opencode now expects an oc-plugin key to be set in package.json.

Steps to reproduce

Run opencode plugin "@devtheops/opencode-plugin-otel":

$ opencode plugin "@devtheops/opencode-plugin-otel"

┌  Install plugin @devtheops/opencode-plugin-otel
│
◇  Plugin package ready
│
■  No plugin targets found
│
■  "@devtheops/opencode-plugin-otel" does not declare supported targets in package.json
│
●  Expected: "oc-plugin": ["server", "tui"] or tuples like [["tui", { ... }]].
│
└  Done

Expected behavior

I expect the plugin to be successfully installed.

Actual behavior

The plugin installation fails because oc-plugin isn't defined in package.json.

Plugin version

0.6.0

Configuration

Relevant log output

Checklist

• I have searched existing issues to ensure this hasn't been reported
• I have redacted any sensitive information (API keys, tokens, etc.)