pr-review plugin: agent_script.py should use Plugin.load() instead of manual skill loading

[xingyaoww]

Problem

The pr-review plugin's agent_script.py loads skills manually via load_project_skills() and passes them directly to AgentContext:

project_skills = load_project_skills(cwd)
agent_context = AgentContext(load_public_skills=True, skills=project_skills)
agent = Agent(llm=llm, tools=tools, agent_context=agent_context, ...)
conversation = Conversation(agent=agent, workspace=cwd, secrets=secrets)

This bypasses the SDK's Plugin system, which provides a proper way to load bundled skills, hooks, and MCP config together via Plugin.load():

from openhands.sdk.plugin import Plugin

plugin = Plugin.load('/path/to/plugin')
agent_context = AgentContext(skills=plugin.skills)
agent = Agent(llm=llm, tools=tools, mcp_config=plugin.mcp_config or {}, agent_context=agent_context)
conversation = Conversation(agent=agent, hook_config=plugin.hooks)

Impact

• The pr-review plugin's skills/ directory (which contains symlinks to codereview-roasted and github-pr-review) is never loaded via the Plugin system.
• Any hooks or MCP config added to the plugin in the future would be silently ignored.
• The plugin directory also lacks a .plugin/plugin.json manifest, which is required by Plugin.load().

Suggested Fix

1. Add .plugin/plugin.json manifest to plugins/pr-review/
2. Update agent_script.py to use Plugin.load() for the pr-review plugin itself
3. Combine plugin skills with project skills before passing to AgentContext
4. Pass plugin.hooks and plugin.mcp_config to Conversation and Agent respectively

The new qa-changes plugin (#135) already follows this pattern and can be used as a reference.

This issue was created by an AI assistant (OpenHands).