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/assets/styles/tokens.css

@@ -37,4 +37,47 @@
   --font-mono: 'JetBrains Mono', ui-monospace, 'Menlo', monospace;
 
   --input-bg: rgba(244, 243, 238, 0.04);
+
+  /* Cosmetic density. comfy=1, compact≈0.78. Used by page chrome that opts in
+     (PageHeader / table cells). Reading via calc() keeps layouts in one place. */
+  --density-scale: 1;
+}
+
+/* Tweaks: density overrides */
+:root[data-density='compact'] { --density-scale: 0.78; }
+
+/* Tweaks: light theme (warm cream, charcoal text). Overrides every surface
+   token so any component that uses var(--bg / --surface / --text / ...) flips
+   without code changes. Components that hard-code rgba(244,243,238,...) will
+   not flip — those should switch to tokens if they care about light mode. */
+:root[data-theme='light'] {
+  --bg:        #F6F4EF;
+  --surface:   #FAF8F2;
+  --elevated:  #FFFFFF;
+  --border:    #E2DED2;
+  --border-hi: #D0CBBC;
+
+  --text:      #1C1B17;
+  --text-dim:  rgba(28, 27, 23, 0.72);
+  --text-mute: rgba(28, 27, 23, 0.50);
+
+  --side-bg:     #F0EDE4;
+  --side-surf:   #FAF8F2;
+  --side-border: #E2DED2;
+  --side-text:   #1C1B17;
+  --side-dim:    rgba(28, 27, 23, 0.62);
+  --side-mute:   rgba(28, 27, 23, 0.42);
+  --side-hover:  rgba(28, 27, 23, 0.05);
+  --side-active: rgba(28, 27, 23, 0.08);
+
+  --accent: #1F8A5B;
+  --accent-fg: #FAF8F2;
+  --signal: #1F8A5B;
+
+  --ok:   #1F8A5B;
+  --warn: #C97F1F;
+  --bad:  #C03A3A;
+  --info: #2A6FDB;
+
+  --input-bg: rgba(28, 27, 23, 0.04);
 }