data/agents/default.json: remove hard-coded shell and reasoning_think from autoLoad

These two are built-in tools always available regardless of autoload.
No need to explicitly load them.

data/agents/default.json

@@ -5,8 +5,6 @@
     "bash -c 'd=$PWD; while [ \"$d\" != / ]; do [ -d \"$d/.beads\" ] && exec bd prime; [ ! -e \"$d/.git\" ] && break; d=$(dirname \"$d\"); done' 2>/dev/null || true"
   ],
   "autoLoad": [
-    "shell",
-    "reasoning_think",
     "file_read",
     "file_write",
     "file_edit",