fix(routing): redirect anonymous users from protected routes + devtools rename

Bug 1: hard-loading / while unauthenticated stayed stuck on "Loading..."
forever. Cause: the _authed layout short-circuits to the spinner when
status is anything other than 'authenticated', which means child routes
never mount. The redirect-on-anonymous useEffect lived only in the
home page (_authed/index.tsx), so it never fired — the layout's spinner
was the last thing rendered.

Fix: add a useEffect to the _authed layout component itself that
navigates to /login on the 'anonymous' transition. The layout's gate
is now: beforeLoad redirects on cold-known-anonymous, useEffect
redirects on post-mount transitions to anonymous (e.g. boot probe
resolves to anonymous after the route already rendered).

Bug 2: console warning that @tanstack/router-devtools moved to
@tanstack/react-router-devtools. Same package, renamed.

Fix: pnpm remove @tanstack/router-devtools && pnpm add -D
@tanstack/react-router-devtools; updated the lazy import in __root.tsx
to point at the new package name.

Plus: TRM_Design_System-handoff/ added to .prettierignore — those files
are immutable source material from claude.ai/design and shouldn't be
reformatted.

.prettierignore

@@ -11,3 +11,7 @@ pnpm-lock.yaml
 public
 src/routeTree.gen.ts
 
+# Design handoff bundle — immutable source material from claude.ai/design.
+# Do not auto-format; preserve as-shipped for reference.
+TRM_Design_System-handoff
+