feat: per-tool settings, persistent settings file, Codex and Antigravity sessions, tokens and hooks (#40 B, C1, C2, D)

Part B: Model Pricing, Hook Configuration and CLAUDE_HOME move from
Settings → Dashboard to the Claude Code tab's AgentHub sub-tab
(ClaudeAgentHubSettings.tsx); CODEX_HOME is editable in Codex → AgentHub.
A home that is or contains the OS home is refused (EBADHOME).

Settings persistence: dashboard-saved settings go to
~/.config/agenthub/settings.env (AGENTHUB_SETTINGS_FILE), outside the plugin
cache an update wipes. Load order: real env > the checkout's .env > that file.
The first CLAUDE_HOME change pins DASHBOARD_DATA_DIR so the DB stays put.

C1: codex-usage.js reads Codex rollout journals into sessions (new column
tool) and token_usage, tracked per file in codex_rollouts; forks deduped by
total vector, sub-agent threads folded into the root; pricing-sync also
prices OpenAI models; PricingSettings with a vendor filter.

C2: codex-hooks.js installs AgentHub's hooks into $CODEX_HOME/hooks.json on
a click, through a stable forwarder; Codex trust is never written. The hook
route creates tool='codex' sessions and folds sub-agent hooks into the root.

D: antigravity-usage.js reads agy's per-conversation SQLite files (tokens
from ModelUsageStats) into tool='antigravity' sessions; antigravity-hooks.js
installs the named hook `agenthub` (PreInvocation, PostToolUse, Stop — never
PreToolUse) into ~/.gemini/config/hooks.json; Settings → Antigravity tab;
Gemini pricing.

Whole-change review fixes: sameOriginGuard on both home PUTs, routers.missing
on a CLAUDE_HOME change, reset-pricing scope, GET /api/sessions?tool=,
clear-data covering the new tables, Codex child-thread events moving no
status, hooks owning status only while current, EFOREIGN for a forwarder
that is not ours, agy quiet window and turn rules, AGENTHUB_SETTINGS_FILE
honoured from .env.

Docs, OpenAPI and the CLAUDE.md marker updated. Server 2141, client 779.

client/src/pages/Sessions.tsx

@@ -72,6 +72,7 @@ import { eventBus } from "../lib/eventBus";
 import { isRemoteDataRefreshMessage } from "../lib/remoteDataEvents";
 import { useDataScope } from "../lib/dataScope";
 import { SessionStatusBadge } from "../components/StatusBadge";
+import { SessionToolBadge } from "../components/SessionToolBadge";
 import { EmptyState } from "../components/EmptyState";
 import { TableRowSkeleton } from "../components/Skeleton";
 import { formatDateTime, formatDuration, truncate, fmtCost } from "../lib/format";
@@ -434,6 +435,7 @@ export function Sessions() {
                           <p className="text-sm font-medium text-fg-secondary">
                             {session.name || `${t("defaultName")}${session.id.slice(0, 8)}`}
                           </p>
+                          <SessionToolBadge tool={session.tool} />
                           {session.source && session.source !== "local" && (
                             <span
                               className="inline-flex items-center gap-1 text-[10px] font-semibold text-sky-700 dark:text-sky-300 bg-sky-500/10 border border-sky-500/25 px-1.5 py-0.5 rounded-full"