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/DiagramEdge.tsx

@@ -23,7 +23,7 @@ export function DiagramEdge({ edge, offsetY = 0, traversed }: DiagramEdgeProps)
       <path
         d={d}
         fill="none"
-        stroke={traversed === true ? '#3D7C47' : '#9CA3AF'}
+        stroke={traversed === true ? 'var(--success)' : 'var(--text-muted)'}
         strokeWidth={traversed === true ? 1.5 : traversed === false ? 1 : 1.5}
         strokeDasharray={traversed === false ? '4,3' : undefined}
         markerEnd={traversed === true ? 'url(#arrowhead-green)' : traversed === false ? undefined : 'url(#arrowhead)'}
@@ -32,7 +32,7 @@ export function DiagramEdge({ edge, offsetY = 0, traversed }: DiagramEdgeProps)
         <text
           x={(pts[0][0] + pts[pts.length - 1][0]) / 2}
           y={(pts[0][1] + pts[pts.length - 1][1]) / 2 + offsetY - 6}
-          fill="#9C9184"
+          fill="var(--text-muted)"
           fontSize={9}
           textAnchor="middle"
         >