Plugin event handler errors corrupt TUI display #12931

Description

Plugin event handlers registered via the plugin system can corrupt the TUI display when they throw errors or write to stderr.

Steps to Reproduce

1. Create a plugin with an event handler that either:
   • Throws an error (sync or async)
   • Calls console.error() to log failures
2. Trigger the event (e.g., session.idle)
3. Observe the error output rendered directly into the TUI chat window

Expected Behavior

• Plugin event handler errors should be caught and logged to the OpenCode log file
• Plugins should have access to a proper logging mechanism instead of relying on console.error()
• A failing plugin should not prevent other plugins from receiving events

Actual Behavior

• Sync throws propagate up and crash the bus subscriber
• Async rejections are completely uncaught (handlers aren't awaited)
• console.error() output goes to stderr, which corrupts the TUI display

Root Cause

In packages/opencode/src/plugin/index.ts, the Bus.subscribeAll callback calls hook["event"]?.() without:

1. awaiting the result (so async errors are uncaught)
2. Wrapping in try-catch (so sync errors propagate)

Additionally, plugins have no log property on PluginInput, so their only logging option is console.error() which writes to stderr.

Example occurance: