Namespace CModuleDebug

Native debug module — QuickJS debugger primitives + cross-thread DebugChannel.

Reviewed final definitions. Notes vs. the previous draft:

• getFrameInfo is now declared (was missing).
• Frame info uses the key column (not col).
• STEP_* constants are actually exported by the native module now.
• EV_PAUSED / EV_RESUMED event-type constants added for notify().
• DebugChannelMain.waitRequest() returns a discriminated union (inspect | resume), never raw control messages.
• waitRequest() throws InternalError (EAGAIN) when stop() is called.