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/e2e/workspace-setup-runtime.spec.ts

@@ -5,7 +5,6 @@ import {
   connectWorkspaceSetupClient,
   createChatAgentFromWorkspaceSetup,
   createStandaloneTerminalFromWorkspaceSetup,
-  createTerminalAgentFromWorkspaceSetup,
   createWorkspaceFromSidebar,
   findWorktreeWorkspaceForProject,
   openHomeWithProject,
@@ -109,36 +108,6 @@ test.describe("Workspace setup runtime authority", () => {
     }
   });
 
-  test("first terminal agent attaches to the created workspace", async ({ page }) => {
-    test.setTimeout(90_000);
-
-    const client = await connectWorkspaceSetupClient();
-    const repo = await createTempGitRepo("workspace-setup-terminal-agent-");
-
-    try {
-      await client.openProject(repo.path);
-      await openWorkspaceSetupDialogFromSidebar(page, repo.path);
-      const agentIdsBefore = new Set((await client.fetchAgents()).entries.map((entry) => entry.agent.id));
-
-      await createTerminalAgentFromWorkspaceSetup(page, {
-        providerLabel: "Claude",
-        prompt: `workspace-setup-terminal-agent-${Date.now()}`,
-      });
-
-      const workspace = await expectCreatedWorkspaceRoute(client, repo.path);
-      const agent = await waitForNewWorkspaceAgent(
-        client,
-        workspace.workspaceDirectory,
-        agentIdsBefore,
-      );
-      expect(agent.cwd).toBe(workspace.workspaceDirectory);
-      expect(agent.cwd).not.toBe(repo.path);
-    } finally {
-      await client.close();
-      await repo.cleanup();
-    }
-  });
-
   test("first terminal attaches to the created workspace", async ({ page }) => {
     test.setTimeout(90_000);