feat: Sprint 4 — scenario planner, report builder, comments, dashboard widgets

What-If Scenario Planner (G5):
- New /projects/[id]/scenario page with side-by-side baseline vs scenario
- simulate mutation: pure cost/hours/headcount/utilization computation
- apply mutation: creates real PROPOSED assignments from scenario
- Impact cards: cost delta, hours delta, headcount, skill coverage %
- Per-resource utilization impact table with over-allocation warnings
- "What-If" button added to project detail page

Custom Report Builder (G7):
- New /reports/builder page with full config panel
- Entity selector (resource/project/assignment), column picker, filter builder
- Dynamic Prisma query with eq/neq/gt/lt/contains/in operators
- Sortable results table with pagination (50/page)
- CSV export via exportReport mutation
- Sidebar nav link under Analytics

Collaboration Layer (G8):
- Comment model in Prisma (entityType/entityId, replies, @mentions, resolved)
- comment router: list, count, create, resolve, delete
- @mention parsing with notification creation + SSE delivery
- CommentInput with @mention autocomplete (arrow nav, Enter/Tab confirm)
- CommentThread with avatar, timestamp, reply, resolve, delete
- Integrated as "Comments" tab in estimate workspace with count badge

Dashboard Widgets:
- BudgetForecastWidget: progress bars per project, burn rate, exhaustion date
- SkillGapWidget: supply vs demand per skill, shortage/surplus indicators
- ProjectHealthWidget: 3-dimension health circles + composite score
- 3 new application use-cases + dashboard router queries
- All registered in widget-registry with lazy imports

Co-Authored-By: claude-flow <ruv@ruv.net>

packages/api/src/router/index.ts

@@ -6,6 +6,7 @@ import { blueprintRouter } from "./blueprint.js";
 import { chargeabilityReportRouter } from "./chargeability-report.js";
 import { computationGraphRouter } from "./computation-graph.js";
 import { clientRouter } from "./client.js";
+import { commentRouter } from "./comment.js";
 import { countryRouter } from "./country.js";
 import { dashboardRouter } from "./dashboard.js";
 import { effortRuleRouter } from "./effort-rule.js";
@@ -18,8 +19,10 @@ import { notificationRouter } from "./notification.js";
 import { orgUnitRouter } from "./org-unit.js";
 import { projectRouter } from "./project.js";
 import { rateCardRouter } from "./rate-card.js";
+import { reportRouter } from "./report.js";
 import { resourceRouter } from "./resource.js";
 import { roleRouter } from "./role.js";
+import { scenarioRouter } from "./scenario.js";
 import { settingsRouter } from "./settings.js";
 import { staffingRouter } from "./staffing.js";
 import { systemRoleConfigRouter } from "./system-role-config.js";
@@ -54,7 +57,10 @@ export const appRouter = createTRPCRouter({
   managementLevel: managementLevelRouter,
   rateCard: rateCardRouter,
   chargeabilityReport: chargeabilityReportRouter,
+  report: reportRouter,
+  scenario: scenarioRouter,
   calculationRule: calculationRuleRouter,
+  comment: commentRouter,
   computationGraph: computationGraphRouter,
   systemRoleConfig: systemRoleConfigRouter,
 });