Error messages incorrectly reports missing wallet and hides actual incompatibility reason

[acogn]

Summary

When a payment requirement is incompatible for reasons other than wallet presence (e.g., unsupported token or network filter), purl reports a wallet-missing style error, even when a wallet is configured.

How to Reproduce

1. Configure a Solana wallet (purl wallet add, set active).
2. Call an endpoint that returns a Solana payment requirement with an unsupported token (e.g. USDT)
3. Run: purl --dry-run <url>.

Actual

Error implies no compatible wallet is configured.

Expected

Error should indicate the true incompatibility reason:

• unsupported token configuration, or
• network filtered out, or
• missing wallet (only when that is the actual cause).

Root Cause

• Negotiator collapsed all incompatibilities into NoCompatibleMethod without reason metadata.
• Token-support failure (TokenConfigNotFound) was reduced to a boolean and discarded.
• CLI converted PurlError to string (anyhow!("{e}")), losing typed error context.