feat: timeline multi-select, demand popover, resource hover card, merged tooltips, dark mode fixes

Major timeline enhancements:
- Right-click drag multi-selection with floating action bar (batch delete/assign)
- DemandPopover for demand strip details (replaces broken "Loading" modal)
- ResourceHoverCard on name hover showing skills, rates, role, chapter
- Merged heatmap+vacation tooltips into unified TimelineTooltip component
- Fixed overbooking blink animation (date normalization, z-index ordering)
- Fixed dark mode sticky column bleed-through in project view
- System roles admin page, notification task management, performance review docs

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

packages/api/src/index.ts

@@ -1,4 +1,4 @@
 export { appRouter, type AppRouter } from "./router/index.js";
-export { createTRPCContext, createTRPCRouter, createCallerFactory, publicProcedure, protectedProcedure, managerProcedure, controllerProcedure, adminProcedure, requirePermission } from "./trpc.js";
+export { createTRPCContext, createTRPCRouter, createCallerFactory, publicProcedure, protectedProcedure, managerProcedure, controllerProcedure, adminProcedure, requirePermission, loadRoleDefaults, invalidateRoleDefaultsCache } from "./trpc.js";
 export { eventBus, emitAllocationCreated, emitAllocationUpdated, emitAllocationDeleted, emitProjectShifted, emitBudgetWarning, flushPendingEvents, cancelPendingEvents } from "./sse/event-bus.js";
 export { anonymizeResource, anonymizeResources, anonymizeUser, getAnonymizationConfig, getAnonymizationDirectory } from "./lib/anonymization.js";