gad:workspace-add

Parse $ARGUMENTS:

• First positional arg = path to add
• --id <name> = optional explicit id (defaults to dirname of path)

1. Validate path exists:

   ls "$PATH_ARG" 2>/dev/null || echo "PATH_NOT_FOUND"
   

   If the path doesn't exist, offer to create it.

2. Check for duplicate: Read planning-config.toml and verify the path isn't already registered. If already present, show the existing entry and exit.

3. Ensure .planning/ exists:

   mkdir -p "$PATH_ARG/.planning"
   

4. Append [[planning.roots]] entry to planning-config.toml:

   [[planning.roots]]
   id = "<id>"
   path = "<path>"
   planningDir = ".planning"
   discover = false
   

5. Confirm:

   ✓ Added [<id>] → <path>/.planning/