feat: analytics parity — tool cost, date ranges, budgets, query explorer, replay, snapshots (v2.4.0)

Analytics parity phases 2–7 (docs/plans/analytics-parity/), built on
138e706 and ported onto v2.3.1:
- Cost by AI tool (?tool= on cost/analytics/stats/workflows, by_tool,
  Codex fast/priority and flex tiers, agenthub_cost_usd_total{tool,model})
- Date ranges (from/to) on cost/analytics/workflows; Analytics range select
  with Today / This week (Monday) / This month (1st) / 7d / 30d / 90d / All /
  Custom; workflow filters carried into workflow-stats.js (read worker)
- Budgets and cost alerts as alert rule types (alert_rules rebuilt without
  its rule_type CHECK), GET /api/budgets/status, rule preview, spend pace,
  status-bar budget chip; rules stay editable in place
- Query Explorer (/query, allowlisted sort, CSV/JSON export) and scheduled
  reports (report_definitions/report_runs, Settings → Reports)
- Session Replay tab and immutable snapshots (session_snapshots, /snapshot/:token)
- Remote Codex sync, push ingest with a hashed token, privacy redaction and
  ignored folders (Settings → Data), Cursor sessions (no cost)
- Read-only MCP server, statusline, Grafana/Prometheus files

Also: resizable sidebar, pet run/wave animations, the workspace home keeps a
half-typed prompt, and the pre-commit hook runs only the related tests for a
small commit.

server/routes/metrics.js

@@ -25,6 +25,7 @@
 const { Router } = require("express");
 const { stmts, db } = require("../db");
 const { getConnectionCount } = require("../websocket");
+const { calculateCost, dailyTokenRows } = require("./pricing");
 
 const router = Router();
 
@@ -192,6 +193,34 @@ router.get("/", (_req, res) => {
     ]
   );
 
+  // Cumulative cost in USD by AI tool and model, priced exactly as
+  // GET /api/pricing/cost prices it (the per-day rate). The code-execution
+  // container time, billed once per org, has no model and is not included.
+  const rules = stmts.listPricing.all();
+  const rowsByTool = new Map();
+  for (const r of dailyTokenRows("+0 minutes", "", [])) {
+    const tool = r.tool || "claude";
+    if (!rowsByTool.has(tool)) rowsByTool.set(tool, []);
+    rowsByTool.get(tool).push(r);
+  }
+  const costSamples = [];
+  for (const [tool, rows] of rowsByTool) {
+    const byModel = new Map();
+    for (const b of calculateCost(rows, rules).breakdown) {
+      byModel.set(b.model, (byModel.get(b.model) || 0) + b.cost);
+    }
+    for (const [model, value] of byModel) {
+      costSamples.push({ labels: { tool, model }, value: Math.round(value * 10000) / 10000 });
+    }
+  }
+  appendMetric(
+    out,
+    "agenthub_cost_usd_total",
+    "Cumulative token cost in USD across all sessions, by AI tool and model.",
+    "counter",
+    costSamples
+  );
+
   res.set("Content-Type", "text/plain; version=0.0.4; charset=utf-8");
   res.send(out.join("\n") + "\n");
 });