feat: metrics dashboards with SVG charts, CSV export, leaderboard (phase 10)

- aggregations over the immutable bountyAwards ledger: totals, weekly
  buckets ($dateTrunc), per-developer and per-customer groupings
- timeline-derived: approval rate, time logged, assigned→approved lead
  time, imported→published atomization lead time, open board depth
- developer + consultant dashboards (admin = global consultant view),
  date-range filters, CSV export of the ledger
- leaderboard (top 10 by bounty) honoring the new leaderboardOptOut
  profile setting
- hand-rolled SVG line and bar charts (~150 lines, no chart library)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

PROGRESS.md

@@ -10,3 +10,4 @@
 - Phase 7 (atomization): circuit breaker (3 fails→open, 60s half-open probe) + retrying bearer JSON client shared by both external services, atomizer client w/ §5.1 coefficient normalization (±0.001 ok, ≤0.05 renormalized, else 502-class), persisted jobs queue (panic-safe, backoff ×3, stale requeue, restart-safe), subdivide/extend endpoints (202 async, re-run replaces unpublished children after confirm), task editing w/ bounty recompute + optional budget cascade, publish single/bulk, WS hub (origin check, 30s heartbeats) + live board, consultant atomization board UI (tree, sliders, sum indicator, modals, shimmer, health gating) — unit + integration green. Fixed tasks unique index: sparse→partial (sparse compound matched every task via customerId).
 - Phase 8 (bounty board + lifecycle): developer board (pool-scoped, filters/search/sort, stale age badges, hide-competing-claims setting, saved filters), claim/withdraw/decline/approve, assign-to-AI via §5.2 client + HMAC-verified idempotent callback w/ artifact ingestion into GridFS, start/submit/abandon/unassign, comments (sanitized, @mentions→notifications), time log, review queue + per-AC checklist on timeline, immutable bountyAwards on approve (humans only), notifications center + bell + WS toasts, my-tasks kanban, task detail page, pool management UI, server-side HTML sanitizer w/ XSS vector tests — full lifecycle integration tests green.
 - Phase 9 (messaging): conversations (dm dedupe/group/project), sanitized rich-text messages, file/image attachments (generic POST /api/v1/files w/ rate limit), per-conversation unread counts + mark-read, chat-file access limited to participants, mentions→notifications, typing indicator over WS inbound relay, two-pane messages UI (contenteditable composer, formatting toolbar, drag&drop upload, inline previews + lightbox, live delivery, polling fallback), user directory search — integration tests green.
+- Phase 10 (metrics): aggregation pipelines over bountyAwards + timelines (totals, weekly $dateTrunc buckets, per-developer/per-customer, approval rate, time logged, assign→approve lead time, atomization lead time, open board depth), CSV export, leaderboard w/ opt-out (profile setting), dependency-free SVG line+bar charts, developer/consultant/admin dashboards — integration tests green.