fix: normalize_step crashes with ValueError when --steps passes plain strings

[willfrey]

Problem

desloppify plan cluster update <name> --steps "step text" "step text" crashes with:

File ".../step_parser.py", line 145, in normalize_step
    return dict(step)
ValueError: dictionary update sequence element #0 has length 1; 2 is required

Repro

desloppify plan cluster update my-cluster --steps "Do thing A" "Do thing B"

Root Cause

normalize_step() in engine/_plan/step_parser.py calls dict(step) which tries to convert a string to a dict. When the --steps CLI arg passes raw strings, they arrive as str not ActionStep (a TypedDict), and dict("string") fails because it interprets each character as a key-value pair.

Workaround

Use --steps-file with a temp file containing numbered steps:

1. Do thing A
2. Do thing B

Fix

In normalize_step, check if step is a string and wrap it as {"title": step} before calling dict(). Or fix the CLI argument parser to construct ActionStep dicts from the string args.