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/openapi.js

@@ -244,7 +244,7 @@ function createOpenApiSpec() {
             tool: {
               type: "string",
               description:
-                "The AI coding CLI that produced the session: `claude` (Claude Code's hooks and imported transcripts), `codex` (Codex's rollout journals and its opt-in hooks) or `antigravity` (agy's conversation files and its opt-in hooks).",
+                "The AI coding CLI that produced the session: `claude` (Claude Code's hooks and imported transcripts), `codex` (Codex's rollout journals and its opt-in hooks) `antigravity` (agy's conversation files and its opt-in hooks) or `cursor` (Cursor's agent transcripts — sessions only, no tokens).",
             },
             agent_count: { type: "integer", nullable: true },
             last_activity: { type: "string", format: "date-time", nullable: true },