add task input form and improve script runner output

- fetch task input definitions from API and render configurable inputs
- boolean inputs render as No/Yes toggle (e.g. delete_source)
- auto-filled inputs (file_path) are hidden from the form
- wrap script output in dark pre/code block with copy button
- fix ffmpeg -nostdin for batch directory processing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

seed/tasks/convert-to-mp3/TASK.md

@@ -26,6 +26,10 @@ inputs:
   file_path:
     type: string
     description: Path to an audio file or directory to convert.
+  delete_source:
+    type: boolean
+    description: Delete source files after successful conversion.
+    default: false
 args: [file_path]
 ---
 

seed/tasks/convert-to-mp3/run.sh

@@ -4,6 +4,7 @@ set -euo pipefail
 # ── Task: Convert To MP3 ──
 
 EXTENSIONS="flac|wav|ogg|wma|aac|m4a|opus|aiff|aif|ape|wv|alac|dsf|dff"
+DELETE_SOURCE="${INPUT_DELETE_SOURCE:-false}"
 
 process_file() {
   local input="$1"
@@ -25,8 +26,12 @@ process_file() {
   fi
 
   echo "Converting: $input → $output"
-  if ffmpeg -i "$input" -codec:a libmp3lame -b:a 320k -map_metadata 0 -id3v2_version 3 -y "$output" 2>/dev/null; then
+  if ffmpeg -nostdin -i "$input" -codec:a libmp3lame -b:a 320k -map_metadata 0 -id3v2_version 3 -y "$output" 2>/dev/null; then
     echo "  Done"
+    if [[ "$DELETE_SOURCE" == "true" ]]; then
+      rm "$input"
+      echo "  Deleted source"
+    fi
   else
     echo "  Failed" >&2
     return 1