feat(operator): command palette, impersonation, incident, tweaks (O.8)

- CommandPalette + useCommandPalette: ⌘K opens a search-and-jump panel over
  real tenants/partners + fixture flags + nav + actions. Arrow keys + Enter
  navigate, Escape/backdrop close. Recents are intentionally omitted for now;
  add when there's something to recent over.
- Impersonation stub: useImpersonation + ImpersonationModal + ImpersonationBanner.
  Modal opens from tenant detail and from the palette. Banner stays at the top
  of the shell until exited. No real OBO token is minted — wiring OAuth Token
  Exchange is tracked as a follow-up.
- IncidentModal + useIncidentModal: opened from the Overview and Infrastructure
  incident banners, renders the mock INCIDENT data with metrics, timeline and
  draft composer.
- TweaksPanel + useTweaks: floating bottom-right panel for theme (dark/light),
  density (comfy/compact), env badge (prod/staging/dev). Saved to localStorage.
- Theme/density apply via [data-theme] + [data-density] overrides in
  tokens.css. Topbar env badge now reads from useTweaks instead of a prop.
- Layout wires ⌘K + ⌘[ at the document level and mounts the palette + modals
  + banner + tweaks panel once for all pages.

apps/operator/layouts/default.vue

@@ -5,6 +5,9 @@
 
 const route = useRoute()
 const { toggle } = useSidebar()
+const { toggle: togglePalette } = useCommandPalette()
+// Touch useTweaks so the persisted theme/density hydrate on first paint.
+useTweaks()
 
 // Derive the active nav row from the route. Matches OpSidebar's `id` keys.
 const currentNav = computed(() => {
@@ -24,13 +27,17 @@ const currentNav = computed(() => {
   return ''
 })
 
-// Keyboard shortcut: ⌘[ toggles sidebar. ⌘K palette lands in O.8.
+// Keyboard shortcuts: ⌘[ toggles sidebar, ⌘K opens the command palette.
 onMounted(() => {
   const onKey = (e: KeyboardEvent) => {
     if ((e.metaKey || e.ctrlKey) && e.key === '[') {
       e.preventDefault()
       toggle()
     }
+    if ((e.metaKey || e.ctrlKey) && e.key.toLowerCase() === 'k') {
+      e.preventDefault()
+      togglePalette()
+    }
   }
   document.addEventListener('keydown', onKey)
   onBeforeUnmount(() => document.removeEventListener('keydown', onKey))
@@ -39,23 +46,32 @@ onMounted(() => {
 
 <template>
   <div class="shell">
-    <OpSidebar :current="currentNav" />
-    <main>
-      <OpTopbar />
-      <div class="content">
-        <slot />
-      </div>
-    </main>
+    <ImpersonationBanner />
+    <div class="cols">
+      <OpSidebar :current="currentNav" />
+      <main>
+        <OpTopbar />
+        <div class="content">
+          <slot />
+        </div>
+      </main>
+    </div>
+    <CommandPalette />
+    <ImpersonationModal />
+    <IncidentModal />
+    <TweaksPanel />
   </div>
 </template>
 
 <style scoped>
 .shell {
   display: flex;
+  flex-direction: column;
   min-height: 100vh;
   background: var(--bg);
   color: var(--text);
 }
+.cols { display: flex; flex: 1; min-height: 0; }
 
 main { flex: 1; min-width: 0; display: flex; flex-direction: column; }
 .content { flex: 1; min-width: 0; overflow-y: auto; }