refactor: UI consistency — shared CSS, design system colors, no inline styles

Phase 1: Extract 6 shared CSS modules (table-section, log-panel,
rate-colors, refresh-indicator, chart-card, section-card) eliminating
~135 duplicate class definitions across 11 files.

Phase 2: Replace all hardcoded hex colors in CSS modules with design
system variables. Strip ~55 hex fallbacks from var() patterns. Fix 4
undefined variable names (--accent, --bg-base, --surface, --bg-surface-raised).

Phase 3: Replace ~45 hardcoded hex values in ProcessDiagram SVG
components with var() CSS custom properties. Fix Dashboard.tsx color prop.

Phase 4: Create CSS modules for AdminLayout, DatabaseAdminPage,
OidcCallback (previously 100% inline). Extract shared PageLoader
component (replaces 3 copy-pasted spinner patterns). Move AppsTab
static inline styles to CSS classes. Extract LayoutShell StarredList styles.

58 files changed, net -219 lines.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/auth/OidcCallback.module.css

@@ -0,0 +1,21 @@
+.page {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  min-height: 100vh;
+  background: var(--bg-body);
+}
+
+.card {
+  padding: 2rem;
+  text-align: center;
+  min-width: 320px;
+}
+
+.heading {
+  margin-bottom: 1rem;
+}
+
+.backButton {
+  margin-top: 16px;
+}