fix: initialize config context in plugin runtime to prevent warnings

The auto-update checker hook calls getConfigDir() which requires the
config context to be initialized via initConfigContext(). When running
in the OpenCode TUI plugin runtime (vs CLI), this initialization never
happened, causing the warning:

"getConfigContext() called before initConfigContext(); defaulting to CLI paths."

This warning would appear when opening folders containing .mulch or .beads
directories because the lifecycle plugins triggered the auto-update checker.

Fix: Call initConfigContext("opencode", null) at plugin startup to ensure
the config context is properly initialized for all hooks and utilities.

Fixes upstream issue where TUI users see spurious bun install warnings.

src/index.ts

@@ -1,3 +1,4 @@
+import { initConfigContext } from "./cli/config-manager/config-context"
 import type { Plugin } from "@opencode-ai/plugin"
 
 import type { HookName } from "./config"
@@ -14,6 +15,8 @@ import { injectServerAuthIntoClient, log } from "./shared"
 import { startTmuxCheck } from "./tools"
 
 const OhMyOpenCodePlugin: Plugin = async (ctx) => {
+  // Initialize config context for plugin runtime (prevents warnings from hooks)
+  initConfigContext("opencode", null)
   log("[OhMyOpenCodePlugin] ENTRY - plugin loading", {
     directory: ctx.directory,
   })