refactor: remove terminal agent concept entirely

Remove the "agent can be a terminal" branching from the entire codebase.
An agent is now always a session-backed chat agent. Standalone terminal
infrastructure (terminal component, ANSI handling, terminal-stream-protocol)
is preserved.

Server: delete ManagedTerminalAgent, AgentKind, TerminalExitDetails,
launchTerminalAgent, registerTerminalAgent, handleTerminalAgentExited,
supportsTerminalMode capability, buildTerminalCreate/ResumeCommand from
all providers, terminal agent persistence/projections.

App: delete terminal-agent-panel.tsx, terminal-agent-reopen-store.ts,
terminal/terminalExit fields on agent state, "Terminal Agents" launcher
section, terminal-agent workspace setup flow, terminal badge in agent list.

CLI: remove terminal column from ls, terminal-agent error from send.

60 files changed, -3592 lines

packages/app/src/components/agent-list.tsx

@@ -15,7 +15,7 @@ import { formatTimeAgo } from "@/utils/time";
 import { shortenPath } from "@/utils/shorten-path";
 import { type AggregatedAgent } from "@/hooks/use-aggregated-agents";
 import { useSessionStore } from "@/stores/session-store";
-import { Archive, SquareTerminal } from "lucide-react-native";
+import { Archive } from "lucide-react-native";
 import { getProviderIcon } from "@/components/provider-icons";
 import { buildHostAgentDetailRoute } from "@/utils/host-routes";
 import { resolveWorkspaceIdByExecutionDirectory } from "@/utils/workspace-execution";
@@ -158,12 +158,6 @@ function SessionRow({
           >
             {agent.title || "New session"}
           </Text>
-          {agent.terminal ? (
-            <SessionBadge
-              label="Terminal"
-              icon={<SquareTerminal size={theme.fontSize.xs} color={theme.colors.foregroundMuted} />}
-            />
-          ) : null}
           {agent.archivedAt ? (
             <SessionBadge
               label="Archived"
@@ -261,7 +255,6 @@ export function AgentList({
         workspaceId,
         target: { kind: "agent", agentId },
         pin: Boolean(agent.archivedAt),
-        requestReopen: agent.terminal && agent.status === "closed",
       });
       router.navigate(route as any);
     },