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/router/notification.ts

@@ -220,7 +220,7 @@ export const notificationRouter = createTRPCRouter({
       });
     }),
 
-  /** Get task counts for the current user */
+  /** Get task counts for the current user — single groupBy instead of 5 counts */
   taskCounts: protectedProcedure.query(async ({ ctx }) => {
     const userId = await resolveUserId(ctx);
     const now = new Date();
@@ -230,11 +230,12 @@ export const notificationRouter = createTRPCRouter({
       category: { in: ["TASK" as const, "APPROVAL" as const] },
     };
 
-    const [open, inProgress, done, dismissed, overdue] = await Promise.all([
-      ctx.db.notification.count({ where: { ...where, taskStatus: "OPEN" } }),
-      ctx.db.notification.count({ where: { ...where, taskStatus: "IN_PROGRESS" } }),
-      ctx.db.notification.count({ where: { ...where, taskStatus: "DONE" } }),
-      ctx.db.notification.count({ where: { ...where, taskStatus: "DISMISSED" } }),
+    const [grouped, overdue] = await Promise.all([
+      ctx.db.notification.groupBy({
+        by: ["taskStatus"],
+        where,
+        _count: true,
+      }),
       ctx.db.notification.count({
         where: {
           ...where,
@@ -244,7 +245,18 @@ export const notificationRouter = createTRPCRouter({
       }),
     ]);
 
-    return { open, inProgress, done, dismissed, overdue };
+    const counts: Record<string, number> = {};
+    for (const g of grouped) {
+      if (g.taskStatus) counts[g.taskStatus] = g._count;
+    }
+
+    return {
+      open: counts["OPEN"] ?? 0,
+      inProgress: counts["IN_PROGRESS"] ?? 0,
+      done: counts["DONE"] ?? 0,
+      dismissed: counts["DISMISSED"] ?? 0,
+      overdue,
+    };
   }),
 
   /** Update task status */