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/pages/Settings.tsx

@@ -223,6 +223,7 @@ export function SettingsPage() {
 			<Modal
 				open={disable2faOpen}
 				onClose={() => setDisable2faOpen(false)}
+				onSubmit={disable2fa}
 				title="Disable 2FA"
 				footer={
 					<>
@@ -246,6 +247,7 @@ export function SettingsPage() {
 			<Modal
 				open={deleteOpen}
 				onClose={() => setDeleteOpen(false)}
+				onSubmit={deleteAccount}
 				title="Delete account"
 				footer={
 					<>