v0.3.0 — native tool cards

Native tool cards. agy tool activity now renders with DSH's own tool-call UI instead of text annotations: terminal cards for run_command, inline diff cards for file writes, read/search cards for the rest, and errored tools as native error results.

Each completed agy tool step cuts the adapter's span with finish: tool-calls addressed to the internal agy_tool mirror; DSH's agent loop dispatches it (replaying the recorded output), records real tool events, and re-calls the provider to continue the same run.