feat: implement relative import resolution with normalized paths and update all test modules

Replace the flat module name-to-path mapping with a proper relative import resolver that handles "./" and "../" prefixes relative to the importer's directory. This is a breaking change: existing imports in user code that assume paths are relative to the entrypoint file will now fail. Stack trace output and host API calls now use the resolved module string instead of the short import name. Update all test fixtures to use "./" relative imports and adjust C test files to pass the full resolved module path to wrenGetVariable.

src/include/wren.h

@@ -92,14 +92,15 @@ typedef enum
 // Reports an error to the user.
 //
 // An error detected during compile time is reported by calling this once with
-// `WREN_ERROR_COMPILE`, the name of the module and line where the error occurs,
-// and the compiler's error message.
+// [type] `WREN_ERROR_COMPILE`, the resolved name of the [module] and [line]
+// where the error occurs, and the compiler's error [message].
 //
-// A runtime error is reported by calling this once with `WREN_ERROR_RUNTIME`,
-// no module or line, and the runtime error's message. After that, a series of
-// `WREN_ERROR_STACK_TRACE` calls are made for each line in the stack trace.
-// Each of those has the module and line where the method or function is
-// defined and [message] is the name of the method or function.
+// A runtime error is reported by calling this once with [type]
+// `WREN_ERROR_RUNTIME`, no [module] or [line], and the runtime error's
+// [message]. After that, a series of [type] `WREN_ERROR_STACK_TRACE` calls are
+// made for each line in the stack trace. Each of those has the resolved
+// [module] and [line] where the method or function is defined and [message] is
+// the name of the method or function.
 typedef void (*WrenErrorFn)(
     WrenVM* vm, WrenErrorType type, const char* module, int line,
     const char* message);
@@ -120,7 +121,7 @@ typedef struct
 } WrenForeignClassMethods;
 
 // Returns a pair of pointers to the foreign methods used to allocate and
-// finalize the data for instances of [className] in [module].
+// finalize the data for instances of [className] in resolved [module].
 typedef WrenForeignClassMethods (*WrenBindForeignClassFn)(
     WrenVM* vm, const char* module, const char* className);
 
@@ -287,7 +288,8 @@ void wrenFreeVM(WrenVM* vm);
 // Immediately run the garbage collector to free unused memory.
 void wrenCollectGarbage(WrenVM* vm);
 
-// Runs [source], a string of Wren source code in a new fiber in [vm].
+// Runs [source], a string of Wren source code in a new fiber in [vm] in the
+// context of resolved [module].
 WrenInterpretResult wrenInterpret(WrenVM* vm, const char* module,
                                   const char* source);
 
@@ -468,10 +470,11 @@ void wrenGetListElement(WrenVM* vm, int listSlot, int index, int elementSlot);
 // an element, use `-1` for the index.
 void wrenInsertInList(WrenVM* vm, int listSlot, int index, int elementSlot);
 
-// Looks up the top level variable with [name] in [module] and stores it in
-// [slot].
+// Looks up the top level variable with [name] in resolved [module] and stores
+// it in [slot].
 void wrenGetVariable(WrenVM* vm, const char* module, const char* name,
                      int slot);
+
 // Sets the current fiber to be aborted, and uses the value in [slot] as the
 // runtime error object.
 void wrenAbortFiber(WrenVM* vm, int slot);