feat(entity): implement path_to() method for entity pathfinding

- Add path_to(target_x, target_y) method to UIEntity class
- Uses existing Dijkstra pathfinding implementation from UIGrid
- Returns list of (x, y) coordinate tuples for complete path
- Supports both positional and keyword argument formats
- Proper error handling for out-of-bounds and no-grid scenarios
- Comprehensive test suite covering normal and edge cases

Part of TCOD integration sprint - gives entities immediate pathfinding capabilities.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/UIEntity.cpp

@@ -377,10 +377,68 @@ PyObject* UIEntity::die(PyUIEntityObject* self, PyObject* Py_UNUSED(ignored))
     Py_RETURN_NONE;
 }
 
+PyObject* UIEntity::path_to(PyUIEntityObject* self, PyObject* args, PyObject* kwds) {
+    static const char* keywords[] = {"target_x", "target_y", "x", "y", nullptr};
+    int target_x = -1, target_y = -1;
+    
+    // Parse arguments - support both target_x/target_y and x/y parameter names
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "ii", const_cast<char**>(keywords), 
+                                     &target_x, &target_y)) {
+        PyErr_Clear();
+        // Try alternative parameter names
+        if (!PyArg_ParseTupleAndKeywords(args, kwds, "|iiii", const_cast<char**>(keywords), 
+                                         &target_x, &target_y, &target_x, &target_y)) {
+            PyErr_SetString(PyExc_TypeError, "path_to() requires target_x and target_y integer arguments");
+            return NULL;
+        }
+    }
+    
+    // Check if entity has a grid
+    if (!self->data || !self->data->grid) {
+        PyErr_SetString(PyExc_ValueError, "Entity must be associated with a grid to compute paths");
+        return NULL;
+    }
+    
+    // Get current position
+    int current_x = static_cast<int>(self->data->position.x);
+    int current_y = static_cast<int>(self->data->position.y);
+    
+    // Validate target position
+    auto grid = self->data->grid;
+    if (target_x < 0 || target_x >= grid->grid_x || target_y < 0 || target_y >= grid->grid_y) {
+        PyErr_Format(PyExc_ValueError, "Target position (%d, %d) is out of grid bounds (0-%d, 0-%d)", 
+                     target_x, target_y, grid->grid_x - 1, grid->grid_y - 1);
+        return NULL;
+    }
+    
+    // Use the grid's Dijkstra implementation
+    grid->computeDijkstra(current_x, current_y);
+    auto path = grid->getDijkstraPath(target_x, target_y);
+    
+    // Convert path to Python list of tuples
+    PyObject* path_list = PyList_New(path.size());
+    if (!path_list) return PyErr_NoMemory();
+    
+    for (size_t i = 0; i < path.size(); ++i) {
+        PyObject* coord_tuple = PyTuple_New(2);
+        if (!coord_tuple) {
+            Py_DECREF(path_list);
+            return PyErr_NoMemory();
+        }
+        
+        PyTuple_SetItem(coord_tuple, 0, PyLong_FromLong(path[i].first));
+        PyTuple_SetItem(coord_tuple, 1, PyLong_FromLong(path[i].second));
+        PyList_SetItem(path_list, i, coord_tuple);
+    }
+    
+    return path_list;
+}
+
 PyMethodDef UIEntity::methods[] = {
     {"at", (PyCFunction)UIEntity::at, METH_O},
     {"index", (PyCFunction)UIEntity::index, METH_NOARGS, "Return the index of this entity in its grid's entity collection"},
     {"die", (PyCFunction)UIEntity::die, METH_NOARGS, "Remove this entity from its grid"},
+    {"path_to", (PyCFunction)UIEntity::path_to, METH_VARARGS | METH_KEYWORDS, "Find path from entity to target position using Dijkstra pathfinding"},
     {NULL, NULL, 0, NULL}
 };
 
@@ -393,6 +451,7 @@ PyMethodDef UIEntity_all_methods[] = {
     {"at", (PyCFunction)UIEntity::at, METH_O},
     {"index", (PyCFunction)UIEntity::index, METH_NOARGS, "Return the index of this entity in its grid's entity collection"},
     {"die", (PyCFunction)UIEntity::die, METH_NOARGS, "Remove this entity from its grid"},
+    {"path_to", (PyCFunction)UIEntity::path_to, METH_VARARGS | METH_KEYWORDS, "Find path from entity to target position using Dijkstra pathfinding"},
     {NULL}  // Sentinel
 };