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/user.ts

@@ -12,9 +12,21 @@ import { Prisma } from "@planarchy/db";
 import { TRPCError } from "@trpc/server";
 import { z } from "zod";
 import { findUniqueOrThrow } from "../db/helpers.js";
-import { adminProcedure, createTRPCRouter, protectedProcedure } from "../trpc.js";
+import { adminProcedure, createTRPCRouter, managerProcedure, protectedProcedure } from "../trpc.js";
 
 export const userRouter = createTRPCRouter({
+  /** Lightweight user list for task assignment (ADMIN + MANAGER) */
+  listAssignable: managerProcedure.query(async ({ ctx }) => {
+    return ctx.db.user.findMany({
+      select: {
+        id: true,
+        name: true,
+        email: true,
+      },
+      orderBy: { name: "asc" },
+    });
+  }),
+
   list: adminProcedure.query(async ({ ctx }) => {
     return ctx.db.user.findMany({
       select: {
@@ -23,11 +35,23 @@ export const userRouter = createTRPCRouter({
         email: true,
         systemRole: true,
         createdAt: true,
+        lastLoginAt: true,
+        lastActiveAt: true,
+        permissionOverrides: true,
       },
       orderBy: { name: "asc" },
     });
   }),
 
+  /** Count of users active in the last 5 minutes */
+  activeCount: adminProcedure.query(async ({ ctx }) => {
+    const fiveMinAgo = new Date(Date.now() - 5 * 60 * 1000);
+    const count = await ctx.db.user.count({
+      where: { lastActiveAt: { gte: fiveMinAgo } },
+    });
+    return { count };
+  }),
+
   me: protectedProcedure.query(async ({ ctx }) => {
     const user = await findUniqueOrThrow(
       ctx.db.user.findUnique({