scripts: enable readline in prompt REPL (read -e)

Supports C-a, C-e, C-u, C-k, M-b, M-f, arrow keys, etc.
Sent prompts and slash commands are added to readline history
so up-arrow recalls previous inputs.

data/scripts/o

@@ -171,16 +171,18 @@ cmd_prompt() {
     echo "Slash commands: /stop /compact /kill /clear /model /backend /cwd /help"
     echo ""
 
-    local buf=""
+    local buf="" line
     while true; do
+        local prompt_str
         if [[ -z "$buf" ]]; then
-            printf "\033[1m>\033[0m "
+            prompt_str=$'\033[1m>\033[0m '
         else
-            printf "  "
+            prompt_str="  "
         fi
-        if ! IFS= read -r line; then
+        if ! IFS= read -e -r -p "$prompt_str" line; then
             # EOF — send remaining buffer if any
             if [[ -n "$buf" ]]; then
+                history -s "$buf"
                 printf '%s\n' "$buf" | ollie-9p write "$path/prompt"
             fi
             printf "\n"
@@ -188,6 +190,7 @@ cmd_prompt() {
         fi
         # Slash commands (only when buffer is empty — first line)
         if [[ -z "$buf" && "$line" == /* ]]; then
+            history -s "$line"
             local cmd="${line#/}"
             case "$cmd" in
                 stop)    echo "stop" | ollie-9p write "$path/ctl"; echo "[stopped]" ;;
@@ -212,6 +215,7 @@ cmd_prompt() {
         fi
         if [[ -z "$line" && -n "$buf" ]]; then
             # Blank line sends accumulated buffer
+            history -s "$buf"
             printf '%s\n' "$buf" | ollie-9p write "$path/prompt"
             buf=""
         elif [[ -z "$line" ]]; then