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/components/ProcessDiagram/NodeToolbar.tsx

@@ -4,7 +4,7 @@ import type { NodeAction, NodeConfig } from './types';
 import styles from './ProcessDiagram.module.css';
 
 const HIDE_DELAY = 150;
-const TRACE_ACTIVE_COLOR = '#1A7F8E';
+const TRACE_ACTIVE_COLOR = 'var(--running)';
 
 interface NodeToolbarProps {
   nodeId: string;
@@ -50,7 +50,7 @@ export function NodeToolbar({
         className={`${styles.nodeToolbarBtn} ${tapActive ? styles.nodeToolbarBtnActive : ''}`}
         title={tapActive ? 'Edit tap' : 'Configure tap'}
         onClick={(e) => { e.stopPropagation(); onAction(nodeId, 'configure-tap'); }}
-        style={tapActive ? { color: '#7C3AED' } : undefined}
+        style={tapActive ? { color: 'var(--purple)' } : undefined}
       >
         <Droplets size={14} />
       </button>