Remove the dead plugin-dispose module and its dedicated test now that V1 plugin migration removed the last production call site. Clean the remaining bootstrap test mocks so src no longer references createPluginDispose.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
Convert the default export from the legacy callable Plugin to the V1 PluginModule shape (`{ id, server }`) documented by opencode's plugin SDK. This aligns oh-my-openagent with the canonical plugin entry format and removes plugin-format legacy debt.
Drop the module-level `let activePluginDispose` cleanup guard: opencode instantiates plugins in a scope-bound Layer per server and dynamic-imports fresh modules on reload, so module-level state is not preserved across reloads. Individual managers already register their own SIGINT/SIGTERM cleanup (skill-mcp-manager, background-agent process-cleanup), so the orphaned createPluginDispose call provided no runtime value.
Remove the non-standard `name` return field that opencode's Hooks interface does not include. The PluginModule's `id` now carries the plugin identity instead.
Drop the unused `lspManager` import that only fed the orphaned createPluginDispose.
Update src/index.test.ts and src/index.telemetry.test.ts to call `plugin.server(ctx)` instead of `plugin(ctx)`, and assert the V1 shape.
YeonGyu-Kim