Add HostLaunchPlan/HostLaunchPlanBuilder to encapsulate host path, package root, working dir, forwarded args and env; add unit tests for builder. Refactor LauncherFlowCoordinator to use HostLaunchPlan when starting hosts, improve IPC handling and startup logic (shorter soft/hard timeouts, more frequent reconnects and shell status polling, activation recovery via existing host). Move argument formatting and environment setup into the plan, include package/working/args metadata in start attempts. Update Commands to prefer ProcessPath for launcher base directory. App and Program: start single-instance activation listener earlier and harden ActivateMainWindow to handle shell initialization state and return richer activation status codes. SingleInstanceService: signal listener readiness (ManualResetEventSlim) and wait briefly when starting, and dispose it. Various logging and minor error handling improvements.
