feat: prefill agent-edit modal, Ctrl+Enter submits modals, improve README

- AgentFormModal: sync form state to current agent values when the modal
  opens (useEffect on open/agent), so edit always shows the agent's
  current name, description, website, icon URL, and max-pending value.
- Modal: add optional onSubmit prop; Ctrl+Enter (or ⌘+Enter) fires it,
  covering AgentFormModal, DecisionModal, and both Settings modals
  (disable 2FA, delete account) without breaking textarea newlines or
  text-input behaviour.
- README: substantially expanded — purpose, capabilities, architecture,
  quick-start with Docker Compose, dev setup, testing, agent integration
  (OpenClaw, generic MCP, REST), and privacy notes.
- TODO.md: remove three completed items (prefill modal, Ctrl+Enter, human
  readme).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

UI/src/components/DecisionModal.tsx

@@ -75,6 +75,7 @@ export function DecisionModal({
 		<Modal
 			open={!!decision}
 			onClose={onClose}
+			onSubmit={submit}
 			title={m.title}
 			footer={
 				<>