fix(panel): task-detail tab state in URL, nav placement, kanban overflow, sidebar divider, tooltip sweep

- Task detail: active tab lives in ?tab= (survives reload, back/forward, and
  prev/next task jumps); prev/next arrows move into the header row next to
  Actions instead of their own row above the title
- Constraints section always starts collapsed (project boilerplate)
- Kanban: native overflow scroll replaces Radix ScrollArea (display:table
  viewport let cards grow past the column and clip); columns share width
  (flex-1, 18rem floor, 24rem cap); dark column colors normalized to /40 tints
- Sidebar footer: drop the Separator doubled with the wrapper's border-t
- Tooltips: self-providing Tooltip root (300ms) + hover hints across sidebar,
  header, task detail, kanban, and every icon-only button that had none

panel/src/components/dashboard/command-center.tsx

@@ -23,6 +23,11 @@ import { RoadmapReviewQueue } from "./roadmap-review-queue";
 import { StrategySignalsPanel } from "./strategy-signals-panel";
 import type { Activity } from "./activity-item";
 import { Button } from "@/components/ui/button";
+import {
+  Tooltip,
+  TooltipContent,
+  TooltipTrigger,
+} from "@/components/ui/tooltip";
 import { UsageOverviewPanel } from "./usage-overview-panel";
 import { ScorecardOverviewPanel } from "./scorecard-overview-panel";
 import { Settings, AlertCircle } from "lucide-react";
@@ -103,11 +108,16 @@ export function CommandCenter() {
           </p>
         </div>
         <div className="flex items-center gap-2">
-          <Link href="/settings" prefetch={false}>
-            <Button variant="ghost" size="icon">
-              <Settings className="h-5 w-5" />
-            </Button>
-          </Link>
+          <Tooltip>
+            <TooltipTrigger asChild>
+              <Link href="/settings" prefetch={false}>
+                <Button variant="ghost" size="icon">
+                  <Settings className="h-5 w-5" />
+                </Button>
+              </Link>
+            </TooltipTrigger>
+            <TooltipContent>Open settings</TooltipContent>
+          </Tooltip>
         </div>
       </div>