feat(mkcapsule): no upper bound on capsule block numbers

Blocks 0..2047, the VM's fast RAM, are the only ones a capsule may not
claim (docs/v4.0.0/NUCLEUS.md 5.2).  The ceiling of 5120 matched no device.
All 36 capsule files still lint clean.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/mkcapsule.c

@@ -405,11 +405,13 @@ static int validate_forth_blocks(const char *fpath,
             block_num     = (int)strtol((const char *)(data + start + 6), NULL, 10);
             line_in_block = 0;
 
-            /* Block number must be in user space: [2048, 5120) */
-            if (block_num < 2048 || block_num >= 5120) {
+            /* Blocks 0..2047 are the VM's fast RAM and the only ones a
+             * capsule may not claim; there is no upper bound
+             * (docs/v4.0.0/NUCLEUS.md 5.2). */
+            if (block_num < 2048) {
                 fprintf(stderr,
-                    "mkcapsule: ERROR: %s:%d: block %d out of user range "
-                    "[2048, 5120)\n",
+                    "mkcapsule: ERROR: %s:%d: block %d is in the VM's fast "
+                    "RAM (0..2047)\n",
                     fpath, file_line, block_num);
                 errors++;
             }