UX-001: sidebar re-entry + inline team/owner creation in wizard

Closes UX-001 (OnboardingWizard CertificateStep dead-end): users no
longer have to navigate away from the wizard and lose their in-flight
state when the required Owner/Team dropdowns are empty.

Layout.tsx
  - Adds persistent 'Setup guide' button in the left sidebar.
  - Clears localStorage 'certctl:onboarding-dismissed' then navigates
    to /?onboarding=1 as a re-entry signal that overrides dismissal.
  - localStorage.removeItem wrapped in try/catch to tolerate storage
    access errors (private browsing, quota, etc.).

DashboardPage.tsx
  - Reads ?onboarding=1 via useSearchParams as a forceOnboarding flag.
  - forceOnboarding bypasses the latched first-run gate so the wizard
    reopens even after dismissal or with certs/issuers already present.
  - onDismiss now also strips ?onboarding=1 via setSearchParams(next,
    { replace: true }) so a page refresh does not relaunch the wizard.

OnboardingWizard.tsx
  - Adds CreateTeamModalInline and CreateOwnerModalInline inside
    CertificateStep. Both wire through React Query: createTeam /
    createOwner mutation on success invalidates ['teams'] / ['owners']
    and calls onCreated(id) so the parent select auto-selects the new
    row as soon as the refetch lands.
  - '+ New team' and '+ New owner' buttons placed next to the select
    labels; empty-state copy replaced with inline 'create one now'
    buttons (no more Link back to /owners /teams).
  - CreateOwner coerces empty teamId to undefined before mutation so
    the server contract matches OwnersPage.

Tests (12 new, all green; total suite 252 passed / 0 failed):
  - Layout.test.tsx (4): Setup guide button renders, clicking it clears
    the dismissal key and navigates to /?onboarding=1, tolerates
    localStorage.removeItem throwing.
  - DashboardPage.test.tsx (4): first-run auto-open, ?onboarding=1
    re-entry after dismissal, onDismiss writes localStorage + strips
    the query param, dismissed-with-no-param stays closed.
  - OnboardingWizard.test.tsx (4): Skip-Skip reaches CertificateStep
    with '+ New team' / '+ New owner' buttons visible; '+ New team'
    happy path with React Query invalidation + parent-select
    auto-select via option-parent traversal (label is a sibling, not
    htmlFor-linked); '+ New owner' happy path pins team_id: undefined
    coercion; Cancel abort never mutates.

Test infrastructure notes:
  - Closure-driven vi.fn().mockImplementation pattern drives the
    post-invalidation refetch: the mutation mock mutates a closure
    variable that the getTeams/getOwners mock reads, so the parent
    select's new <option> exists by the time the refetch lands.
  - Anchored regex (/^Create Team$/, /^Create Owner$/) disambiguates
    the modal submit from the '+ New team' / '+ New owner' triggers.

Verification gates (all green):
  - vitest run: 252 passed / 0 failed (8 files, 13.98s)
  - tsc --noEmit: 0 errors
  - vite build: clean production bundle (851.77 kB js / 226.81 kB gzip)

No new runtime dependencies. Frontend-only change.

web/src/components/Layout.tsx

@@ -1,4 +1,4 @@
-import { NavLink, Outlet } from 'react-router-dom';
+import { NavLink, Outlet, useNavigate } from 'react-router-dom';
 import { useAuth } from './AuthProvider';
 import logo from '../assets/certctl-logo.png';
 
@@ -35,6 +35,12 @@ function Icon({ d }: { d: string }) {
 
 export default function Layout() {
   const { authRequired, logout } = useAuth();
+  const navigate = useNavigate();
+
+  const openSetupGuide = () => {
+    try { localStorage.removeItem('certctl:onboarding-dismissed'); } catch { /* noop */ }
+    navigate('/?onboarding=1');
+  };
 
   return (
     <div className="flex h-screen overflow-hidden">
@@ -71,6 +77,18 @@ export default function Layout() {
           ))}
         </nav>
 
+        <div className="px-3 pb-2 pt-2 border-t border-white/10">
+          <button
+            type="button"
+            onClick={openSetupGuide}
+            title="Reopen the onboarding wizard"
+            className="w-full flex items-center gap-3 px-3 py-2 text-[13px] rounded text-sidebar-text hover:text-white hover:bg-white/10 transition-all duration-150"
+          >
+            <Icon d="M9.663 17h4.673M12 3v1m6.364 1.636l-.707.707M21 12h-1M4 12H3m3.343-5.657l-.707-.707m2.828 9.9a5 5 0 117.072 0l-.548.547A3.374 3.374 0 0014 18.469V19a2 2 0 11-4 0v-.531c0-.895-.356-1.754-.988-2.386l-.548-.547z" />
+            Setup guide
+          </button>
+        </div>
+
         <div className="px-5 py-3 border-t border-white/10 flex items-center justify-between">
           <span className="text-[10px] text-brand-300/60 font-mono">certctl</span>
           {authRequired && (