Add Decisions and Workstreams reference docs with heading help wiring

- Remove residual constitution footnote from progress page header
- Create src/docs/decisions.md: types, statuses, resolution history chart,
  filter bar, card anatomy, Decision Health KPI, escalation protocol
- Create src/docs/workstreams.md: status distribution chart, filter bar,
  table columns, dependency graph, create/update patterns
- Wire withDocHelp(h1) on Decisions and Workstreams pages pointing to new docs
- Add both pages to Reference nav section in observablehq.config.js

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dashboard/observablehq.config.js

@@ -10,6 +10,8 @@ export default {
       name: "Reference",
       pages: [
         { name: "Live Data", path: "/docs/live-data" },
+        { name: "Workstreams", path: "/docs/workstreams" },
+        { name: "Decisions", path: "/docs/decisions" },
         { name: "Decision Health", path: "/docs/decisions-kpi" },
         { name: "Progress Log", path: "/docs/progress-log" },
       ],