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.

client/src/i18n/locales/en/sessions.json

@@ -54,6 +54,55 @@
     "copyId": "Copy session ID",
     "copyFolder": "Copy folder path"
   },
+  "replay": {
+    "tab": "Replay",
+    "loading": "Loading events…",
+    "label": "Session replay",
+    "truncated": "Replaying the newest {{shown}} of {{total}} events.",
+    "start": "Jump to start (Home)",
+    "back": "Step back (←)",
+    "play": "Play (Space)",
+    "pause": "Pause (Space)",
+    "forward": "Step forward (→)",
+    "end": "Jump to end (End)",
+    "speed": "Playback speed",
+    "position": "{{at}} / {{n}}",
+    "scrubber": "Event position",
+    "minimap": "Lifecycle markers",
+    "marker": {
+      "SessionStart": "Session start",
+      "UserPromptSubmit": "Prompt",
+      "Compaction": "Compaction",
+      "SubagentStop": "Subagent done",
+      "APIError": "API error",
+      "Stop": "Turn end"
+    },
+    "state": {
+      "status": "Status",
+      "tool": "Running tool",
+      "prompts": "Prompts",
+      "errors": "Errors",
+      "compactions": "Compactions",
+      "elapsed": "Elapsed",
+      "toolCounts": "Tool calls so far"
+    }
+  },
+  "snapshot": {
+    "create": "Snapshot",
+    "hint": "Freeze this session into a read-only copy with a share link",
+    "title": "Create a snapshot",
+    "body": "Freezes this session as it is now — its agents, events, stats and cost — into a read-only copy under a private link. Later activity does not change it, and it survives Clear Data.",
+    "redactPaths": "Redact file paths (working directory, transcript and file paths)",
+    "confirm": "Create and copy link",
+    "cancel": "Cancel",
+    "open": "Open snapshot",
+    "notFound": "Snapshot not found",
+    "banner": "Snapshot taken {{date}}",
+    "bannerBody": "A read-only copy of the session as it was then. Nothing here updates.",
+    "redacted": "Paths redacted",
+    "openLive": "Open live session",
+    "timeline": "Timeline ({{n}})"
+  },
   "exportCsv": "CSV",
   "exportJson": "JSON",
   "exportCapped": "The file holds {{shown}} of {{total}} sessions (the export limit) — narrow the filters to export the rest.",