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.

scripts/hook-handler.js

@@ -1,7 +1,7 @@
 #!/usr/bin/env node
 
 /**
- * Claude Code hook handler.
+ * Claude Code (and Codex, and Antigravity) hook handler.
  * Receives hook event JSON on stdin and forwards it to every live Agent
  * Dashboard server. Designed to fail silently so it never blocks Claude
  * Code, and to fan out across multiple dashboards that use **different**
@@ -22,6 +22,11 @@
 const http = require("http");
 
 const hookType = process.argv[2] || "unknown";
+// Codex runs this through `<CODEX_HOME>/agenthub-hook.sh <Event>`, which adds
+// `codex` (server/lib/codex-hooks.js), Antigravity through
+// `~/.gemini/config/agenthub-hook.sh`, which adds `antigravity`
+// (server/lib/antigravity-hooks.js); Claude Code passes no second argument.
+const tool = ["codex", "antigravity"].includes(process.argv[3]) ? process.argv[3] : undefined;
 
 /**
  * Resolve every live dashboard server's port via the discovery file. Falls
@@ -54,6 +59,7 @@ process.stdin.on("end", () => {
   const payload = JSON.stringify({
     hook_type: hookType,
     data: parsedData,
+    ...(tool && { tool }),
   });
   const contentLength = Buffer.byteLength(payload);