Fix plugin.json userConfig schema — missing required `type` and `title` fields

[cdubiel08]

Problem

After PR #689 merged (userConfig for secure token storage), the plugin fails validation:

❯ userConfig.github_token.type: Invalid option: expected one of "string"|"number"|"boolean"|"directory"|"file"
❯ userConfig.github_token.title: Invalid input: expected string, received undefined

The userConfig.github_token entry in .claude-plugin/plugin.json is missing two required fields: type and title.

Root Cause

The official Claude Code docs show the old schema (just description + sensitive), but the runtime validator now requires type and title as well. This was confirmed via Anthropic's own PR #831.

Fix

Add the two missing fields:

"userConfig": {
  "github_token": {
    "title": "GitHub Token",
    "type": "string",
    "description": "...",
    "sensitive": true
  }
}

Research

thoughts/shared/research/2026-03-25-userconfig-manifest-schema-validation.md

[cdubiel08]

Implementation Plan

https://github.com/cdubiel08/ralph-hero/blob/main/thoughts/shared/plans/2026-03-25-GH-0690-plugin-json-userconfig-schema-fix.md

Single-phase fix. Adds "title": "GitHub Token" and "type": "string" to userConfig.github_token in plugin/ralph-hero/.claude-plugin/plugin.json. No build step required; verified with claude plugin validate.