fix: avoid IPC mode when isolation is none

[Lojhan]

Summary

• derive shared resource execution mode from PluginContext.configs.isolation
• run shared resources in-process for isolation: none and keep IPC behavior for process isolation
• reset shared resource runtime during teardown so repeated poku(...) invocations do not leak state
• add focused coverage for execution mode behavior and the isolation none integration path

What changed

• wire sharedResources() setup to switch between process and in-process modes automatically
• guard IPC setup and IPC-only request paths when running in-process
• preserve method-call parity in in-process mode by returning async bound method wrappers
• keep the newer codec/config support from main while layering the isolation-aware execution-mode fix on top
• add test/unit/execution-mode.test.ts and extend the integration suite with an isolation none case

Validation

• npm test