T14/Bug #4 #5 #6 #8 #10: commit in-flight worker fixes (agents _all sentinel, settings useThemeStore, 5 detail route registrations)

Continuation of the T10 test report fixes (45d0810). The prior workers
for these bugs wrote the code but died before committing. This commit
captures their work and additionally restores a GET /:id/permissions
route that the prior helper-script accidentally deleted.

- Bug #4 HIGH: GET /api/agents/_all/activity now skips the WHERE clause
  when the SPA passes '_all' as the id.
- Bug #5 MED: Settings > Appearance tab now reads/writes useThemeStore
  (Zustand) so theme changes are consistent with the command palette.
- Bug #6 HIGH: /projects/:id detail page now exists. Plus 4 sibling
  detail pages (tasks/:id, habits/:id, notes/:id, canvas/:id) wired
  into the route tree.
- Bug #8 MED: GET /api/agents/activity (bare path) now returns the
  last 100 activity items instead of falling into /:id/activity with
  id='activity' (which failed the UUID cast).
- Bug #10 LOW: tasks/:id, habits/:id, notes/:id, canvas/:id detail
  pages are now committed (the worker that wrote them never committed).
- graph.tsx and index.tsx overlap with earlier committed fixes
  (t_cc5d9887 and t_296f0121); changes are additive and don't regress.

Also restores GET /api/agents/:id/permissions which the prior helper
script accidentally removed when reformatting agents.ts.

Parent: t_e1cbd87d

apps/web/src/routes/_app/canvas/$id.tsx

@@ -0,0 +1,70 @@
+import { createRoute, useParams, useNavigate } from "@tanstack/react-router";
+import { Route as appRoute } from "../../_app";
+import { useApiQuery } from "@/lib/api";
+import { Button } from "@/components/ui/button";
+import { Badge } from "@/components/ui/badge";
+import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
+import { Separator } from "@/components/ui/separator";
+import { ArrowLeft, Layout, Layers } from "lucide-react";
+import type { Canvas } from "@/lib/types";
+import { format, parseISO } from "date-fns";
+
+function CanvasDetail() {
+  const { id } = useParams({ from: Route.id });
+  const navigate = useNavigate();
+  const { data: canvas, isLoading } = useApiQuery<Canvas>(["canvas", id], "/canvas/" + id);
+
+  if (isLoading) return <div className="p-8 text-center text-muted-foreground">Loading...</div>;
+  if (!canvas) return <div className="p-8 text-center text-muted-foreground">Canvas not found</div>;
+
+  const blockCount = canvas.cards?.length || 0;
+
+  return (
+    <div className="max-w-2xl mx-auto p-6 space-y-6">
+      <Button variant="ghost" onClick={() => navigate({ to: "/canvas" })} className="w-fit">
+        <ArrowLeft className="h-4 w-4 mr-2" /> Back to Canvas
+      </Button>
+      <Card>
+        <CardHeader>
+          <div className="flex items-center gap-3">
+            <Layout className="h-6 w-6 text-muted-foreground" />
+            <CardTitle className="text-2xl">{canvas.name}</CardTitle>
+            <Badge variant="secondary">{canvas.mode}</Badge>
+          </div>
+        </CardHeader>
+        <CardContent className="space-y-4">
+          {canvas.description && (
+            <div>
+              <h3 className="text-sm font-semibold text-muted-foreground mb-1">Description</h3>
+              <p className="text-sm whitespace-pre-wrap">{canvas.description}</p>
+            </div>
+          )}
+          <Separator />
+          <div className="grid grid-cols-2 gap-4 text-center">
+            <div className="p-3 bg-muted/50 rounded-lg">
+              <Layers className="h-5 w-5 mx-auto mb-1 text-muted-foreground" />
+              <p className="text-2xl font-bold">{blockCount}</p>
+              <p className="text-xs text-muted-foreground">Blocks</p>
+            </div>
+            <div className="p-3 bg-muted/50 rounded-lg">
+              <Layout className="h-5 w-5 mx-auto mb-1 text-muted-foreground" />
+              <p className="text-2xl font-bold capitalize">{canvas.mode}</p>
+              <p className="text-xs text-muted-foreground">Mode</p>
+            </div>
+          </div>
+          <Separator />
+          <div className="text-xs text-muted-foreground space-y-1">
+            <p>Created: {format(parseISO(canvas.createdAt), "MMM d, yyyy HH:mm")}</p>
+            <p>Updated: {format(parseISO(canvas.updatedAt), "MMM d, yyyy HH:mm")}</p>
+          </div>
+        </CardContent>
+      </Card>
+    </div>
+  );
+}
+
+export const Route = createRoute({
+  getParentRoute: () => appRoute,
+  path: "canvas/$id",
+  component: CanvasDetail,
+});