Proposal: Replace brittle JSON state with robust artifact inference in setup

[moisgobg]

Problem Description
The current setup.toml command relies on a brittle setup_state.json file to manage setup progress and state. This approach has several drawbacks:

• If the JSON file is deleted or out of sync, the setup process gets confused, forcing users to restart or manually patch the state.
• Writing to and reading from a state file frequently wastes tokens and adds unnecessary file-writing tool calls.

Expected Behavior
Instead of a state file, the agent should perform an artifact audit by checking the physical presence of artifacts (like product.md, tech-stack.md, workflow.md, index.md, and tracks/), the agent can deterministically map the project state and seamlessly resume setup.