fix: show Command Bank in main pos menu; fix pos bank run crash

- bin/pos: _pos_category_list now emits category-less tools (pos-bank,
  pos-config, pos-tree) as sorted menu entries with an empty subcommand
  column, deduped against real categories (pos-ai). bank previously
  never appeared in the bare 'pos' menu.
- bin/pos-bank: fixed invalid 'local name="" -a cli_params=()' at
  cmd_run (line 150) — bash rejected '-a' after an assignment, crashing
  every 'pos bank run' with 'local: -a: not a valid identifier'.
  Split into 'local name=""' + 'local -a cli_params=()'.
- tests/t-bank.sh: added B12-B14 covering cmd_run (no-params,
  missing-command, param substitution) — would have caught the crash.
- AGENT_TODO.md: bank feature moved to Done.

bin/pos

@@ -28,6 +28,9 @@ _pos_commands() {
 # ── Category list (sorted, filename-derived) ─────────────────────
 # Nested sub-tools (pos-<cat>-<a>-<b> where pos-<cat>-<a> exists) are
 # omitted from the cheat-sheet line — they are shown under their parent tool.
+# Category-less tools (pos-bank, pos-config, pos-tree) are emitted as their
+# own line with an empty subcommand column; a name already present as a
+# category (pos-ai vs the ai category built from pos-ai-*) is NOT duplicated.
 _pos_category_list() {
     local -A cats=()
     local cmd cat f
@@ -35,7 +38,10 @@ _pos_category_list() {
         [ -x "$f" ] || continue
         cmd="${f##*/pos-}"
         cat="${cmd%%-*}"
-        [ "$cat" = "$cmd" ] && continue
+        if [ "$cat" = "$cmd" ]; then
+            cats["$cmd"]="${cats[$cmd]:-}"
+            continue
+        fi
         cats["$cat"]+="${cmd#*-} "
     done
     local c subs joined s s2 top=() is_nested
@@ -208,6 +214,8 @@ EXAMPLES
 
   pos tree                                Show the command tree (categories + subcommands)
 
+  pos bank run <name>                     Run a saved command from the bank
+
   pos docker vbox create lab1              Create disposable Docker VM
   pos docker vbox create lab1 --dir .      Create VM using current directory
   pos docker vbox enter lab1               Shell into a Docker VM