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/components/OpTopbar.vue

@@ -1,12 +1,9 @@
 <script setup lang="ts">
-type Env = 'prod' | 'staging' | 'dev'
-
-withDefaults(
-  defineProps<{ env?: Env; oncall?: boolean }>(),
-  { env: 'prod', oncall: true },
-)
+withDefaults(defineProps<{ oncall?: boolean }>(), { oncall: true })
 
 const { user } = useOidcAuth()
+const { state: tweaks } = useTweaks()
+const { open: openPalette } = useCommandPalette()
 
 const ENVS = {
   prod:    { label: 'PROD',    fg: 'var(--text)', bg: 'rgba(244,243,238,0.08)', border: 'rgba(244,243,238,0.15)' },
@@ -14,11 +11,7 @@ const ENVS = {
   dev:     { label: 'DEV',     fg: '#D4AAFF',     bg: 'rgba(159,98,212,0.18)',  border: 'rgba(159,98,212,0.36)' },
 } as const
 
-function openPalette() {
-  // ⌘K palette lands in O.8 — this is the trigger surface.
-  // eslint-disable-next-line no-console
-  console.log('[palette] open requested')
-}
+const env = computed(() => tweaks.value.env)
 </script>
 
 <template>