feat: switch to 64-bit integers and dynamic memory

Co-authored-by: aider (openrouter/deepseek/deepseek-v4-pro) <aider@aider.chat>

forth_dict.c

@@ -1,11 +1,11 @@
 #include "forth.h"
 
 Word* add_primitive(const char* name, void (*code)(Word*), uint8_t flags) {
-    if (dict_idx >= DICT_SIZE) {
-        printf("Dictionary full\n");
-        return NULL;
+    Word* w = malloc(sizeof(Word));
+    if (!w) {
+        fprintf(stderr, "Out of memory\n");
+        exit(1);
     }
-    Word* w = &dict[dict_idx++];
     w->prev = dict_head;
     dict_head = w;
 
@@ -21,7 +21,7 @@ Word* add_primitive(const char* name, void (*code)(Word*), uint8_t flags) {
 
 Word* lookup_word(const char* name) {
     for (Word* w = dict_head; w != NULL; w = w->prev) {
-        if (w->flags & (1 << 6)) continue; // Skip hidden words
+        if (w->flags & (1 << 6)) continue;
         if (strcmp(w->name, name) == 0) return w;
     }
     return NULL;