…ebug support

   - Add MSDebugServer implementing the Debug Adapter Protocol over TCP,
     with launch/attach modes, breakpoints, step-over/step-in/step-out,
     variable inspection, exception breakpoints, and watch expressions
   - Add multi-thread DAP support: register/unregister threads, per-thread
     pause states, sync and async stepping modes (sync blocks in place,
     async snapshots state and resumes on a new thread)
   - Refactor DebugContext into a full thread-aware debug state manager with
     per-thread StepMode, ThreadDebugState, and a thread registry for DAP
   - Add DaemonManager lifecycle listeners and thread-aware waitForThreads,
     so the debug session stays alive while background threads run
   - Extract spawnExecutionThread() to centralize execution thread lifecycle
     (run, await daemons, signal completion) in one place
   - Fix StackTraceManager thread affinity: remove isDebugAdopted flag so
     background threads (x_new_thread) get their own STM instead of sharing
     the main thread's, which was corrupting call depth for step-over
   - Fix skippingResume flag: clear unconditionally on source line change
     rather than requiring shouldStop=true, which blocked step-over returns
   - Add StackTraceFrame.getTarget() for debugger source mapping
   - Add Breakpoint condition/hitCount/logMessage support
   - Wire up cmdline interpreter (--debug flag) and lang server for DAP
   - Add DAPTestHarness and dual sync/async integration tests for step-over
     and multi-thread step-over scenarios
   - Add debugger dependency (lsp4j.debug) to pom.xml