Replace direct fprintf(stderr) calls in wrenDebugPrintStackTrace with invocations of the host-provided errorFn callback, passing WREN_ERROR_RUNTIME for the error message and WREN_ERROR_STACK_TRACE for each stack frame. Introduce the WrenErrorType enum in wren.h with WREN_ERROR_COMPILE, WREN_ERROR_RUNTIME, and WREN_ERROR_STACK_TRACE values, update the WrenErrorFn typedef to accept a type parameter, and modify reportError in cli/vm.c to switch on the error type for formatted output. Adjust wrenDebugPrintStackTrace signature to take WrenVM* instead of ObjFiber* to access the config, and update all call sites accordingly.
Remove the `WrenVM* vm` parameter from `wrenValueBufferInit`, `wrenByteBufferInit`,
`wrenIntBufferInit`, `wrenStringBufferInit`, `wrenSymbolTableInit`,
`wrenMethodBufferInit`, `wrenStringFind`, and `wrenDebugPrintStackTrace`
functions across the compiler, core, debug, utils, value, and VM modules.
Update all call sites and macro definitions to match the simplified signatures,
eliminating dead parameters that were never used within the function bodies.
Separate Wren VM library sources from CLI tool sources by moving them into
src/vm/ and src/cli/ subdirectories respectively. Update the Makefile to use
separate wildcard patterns for each directory, generate distinct object file
paths under build/vm/ and build/cli/, and adjust include paths to src/include.
Also update the Xcode project file to reference the new file locations.
