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/ImpersonationModal.vue

@@ -0,0 +1,158 @@
+<script setup lang="ts">
+const { candidate, cancel, confirm } = useImpersonation()
+const reason = ref('Customer reported issue — investigating')
+const asUser = ref('first-user@example.com · Owner')
+
+watch(candidate, (v) => {
+  if (v) {
+    reason.value = 'Customer reported issue — investigating'
+  }
+})
+
+function onConfirm() {
+  if (!reason.value.trim()) return
+  confirm(reason.value.trim(), asUser.value)
+}
+</script>
+
+<template>
+  <Teleport to="body">
+    <div v-if="candidate" class="backdrop" @click="cancel">
+      <div class="modal" role="dialog" :aria-label="`Impersonate inside ${candidate.name}`" @click.stop>
+        <header>
+          <div>
+            <Eyebrow>Operator action · logged</Eyebrow>
+            <h2>Impersonate inside {{ candidate.name }}</h2>
+          </div>
+          <button class="x" type="button" aria-label="Close" @click="cancel">
+            <UiIcon name="x" :size="12" />
+          </button>
+        </header>
+
+        <div class="body">
+          <div class="warn">
+            <UiIcon name="shield" :size="15" />
+            <p>
+              You'll see <strong>{{ candidate.name }}</strong>'s workspace exactly as one of their users sees it.
+              Any state-changing action will be flagged in their audit log as an operator action with your name
+              attached. <Mono dim>// stub — no real session is created</Mono>
+            </p>
+          </div>
+
+          <label class="field">
+            <span>Impersonate as</span>
+            <input v-model="asUser" type="text" />
+          </label>
+
+          <label class="field">
+            <span>Reason (required)</span>
+            <input v-model="reason" type="text" />
+          </label>
+
+          <Mono dim class="note">// logged as op.impersonate · session expires after 30 min idle</Mono>
+        </div>
+
+        <footer>
+          <UiButton variant="ghost" @click="cancel">Cancel</UiButton>
+          <UiButton variant="danger" :disabled="!reason.trim()" @click="onConfirm">
+            <template #leading><UiIcon name="key" :size="13" /></template>
+            Enter impersonation mode
+          </UiButton>
+        </footer>
+      </div>
+    </div>
+  </Teleport>
+</template>
+
+<style scoped>
+.backdrop {
+  position: fixed;
+  inset: 0;
+  background: rgba(0, 0, 0, 0.55);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 24px;
+  z-index: 180;
+}
+.modal {
+  width: 100%;
+  max-width: 520px;
+  background: var(--elevated);
+  border: 1px solid var(--border);
+  border-radius: 10px;
+  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.5);
+  display: flex;
+  flex-direction: column;
+  overflow: hidden;
+}
+header {
+  padding: 16px 20px;
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-start;
+  border-bottom: 1px solid var(--border);
+}
+h2 { margin: 4px 0 0 0; font-family: var(--font-display); font-weight: 600; font-size: 17px; }
+.x {
+  width: 26px; height: 26px;
+  border: 0; border-radius: 6px; background: transparent;
+  color: var(--text-mute); cursor: pointer;
+  display: inline-flex; align-items: center; justify-content: center;
+}
+.x:hover { background: var(--surface); color: var(--text); }
+
+.body {
+  padding: 16px 20px;
+  display: flex;
+  flex-direction: column;
+  gap: 14px;
+}
+
+.warn {
+  display: flex;
+  align-items: flex-start;
+  gap: 10px;
+  padding: 12px 14px;
+  background: rgba(226, 48, 48, 0.06);
+  border: 1px solid rgba(226, 48, 48, 0.24);
+  border-left: 3px solid var(--bad);
+  border-radius: 6px;
+  color: var(--bad);
+}
+.warn p { margin: 0; font-size: 12px; color: var(--text-dim); line-height: 1.55; }
+.warn strong { color: var(--text); }
+
+.field { display: flex; flex-direction: column; gap: 6px; }
+.field span {
+  font-family: var(--font-mono);
+  font-size: 10px;
+  letter-spacing: 0.12em;
+  text-transform: uppercase;
+  color: var(--text-mute);
+  font-weight: 500;
+}
+.field input {
+  height: 34px;
+  padding: 0 12px;
+  border: 1px solid var(--border);
+  background: var(--input-bg);
+  color: var(--text);
+  border-radius: 6px;
+  font-family: inherit;
+  font-size: 13px;
+  outline: 0;
+}
+.field input:focus { border-color: var(--border-hi); }
+
+.note { padding-top: 2px; }
+
+footer {
+  padding: 12px 20px;
+  display: flex;
+  justify-content: flex-end;
+  gap: 8px;
+  border-top: 1px solid var(--border);
+  background: var(--surface);
+}
+</style>