feat(compat): package rename compatibility layer for oh-my-opencode → oh-my-openagent

- Add legacy plugin startup warning when oh-my-opencode config detected
- Update CLI installer and TUI installer for new package name
- Split monolithic config-manager.test.ts into focused test modules
- Add plugin config detection tests for legacy name fallback
- Update processed-command-store to use plugin-identity constants
- Add claude-code-plugin-loader discovery test for both config names
- Update chat-params and ultrawork-db tests for plugin identity

Part of #2823

src/index.ts

@@ -12,7 +12,7 @@ import { createPluginDispose, type PluginDispose } from "./plugin-dispose"
 import { loadPluginConfig } from "./plugin-config"
 import { createModelCacheState } from "./plugin-state"
 import { createFirstMessageVariantGate } from "./shared/first-message-variant"
-import { injectServerAuthIntoClient, log } from "./shared"
+import { injectServerAuthIntoClient, log, logLegacyPluginStartupWarning } from "./shared"
 import { startTmuxCheck } from "./tools"
 
 let activePluginDispose: PluginDispose | null = null
@@ -23,6 +23,7 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
   log("[OhMyOpenCodePlugin] ENTRY - plugin loading", {
     directory: ctx.directory,
   })
+  logLegacyPluginStartupWarning()
 
   injectServerAuthIntoClient(ctx.client)
   startTmuxCheck()