fix: event-loop freezes, plugin-install boot crash, tmux attach/scrollbar, Codex transcripts

- GET /api/workflows: one LEAD() window pass in a read worker (read-pool.js,
  workflow-stats.js); idx_events_session restored, idx_events_tool added
- compat-sqlite gains function/pluck/readonly so a plugin install without a
  better-sqlite3 build boots again; antigravity-usage uses db.js's Database
- install-hooks adds no checkout hooks while the agenthub plugin is enabled
  (events were doubled)
- terminal attach runs the live tmux server's own binary; the pane scrollbar
  gets a visible 2-column style, and claude panes start with
  CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN=1 so tmux keeps history to scroll
- Codex sessions' conversation in GET /api/sessions/:id/transcript
- Codex/Antigravity sessions claimed by their workspace without hooks
- UI-audit follow-ups, docs and OpenAPI

client/src/pages/__tests__/ActivityFeed.agents.test.ts

@@ -0,0 +1,32 @@
+/**
+ * @file ActivityFeed.agents.test.ts
+ * @description The Activity feed asks for agent labels by agent, not by
+ * session: a subagent spawned later in a session already on screen is fetched
+ * too, and an agent already asked about is not asked for again.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+import { describe, it, expect } from "vitest";
+import { agentsToFetch } from "../ActivityFeed";
+
+describe("agentsToFetch", () => {
+  it("asks again for a session once a new agent of it appears", () => {
+    const asked = new Set(["s1-main"]);
+    const events = [
+      { session_id: "s1", agent_id: "s1-main" },
+      { session_id: "s1", agent_id: "s1-sub-late" },
+      { session_id: "s2", agent_id: null },
+    ];
+    expect(agentsToFetch(events, asked)).toEqual({
+      agentIds: ["s1-sub-late"],
+      sessionIds: ["s1"],
+    });
+  });
+
+  it("asks nothing when every agent on screen is known", () => {
+    expect(agentsToFetch([{ session_id: "s1", agent_id: "a" }], new Set(["a"]))).toEqual({
+      agentIds: [],
+      sessionIds: [],
+    });
+  });
+});