refactor: rename swift → cortex in code and documentation

Complete rename of "swift" terminology to "cortex" across the codebase:

Code Changes:
- Rename directories: lib/swift → lib/cortex, components/swift → components/cortex
- Rename API routes: /api/swift/* → /api/cortex/*
- Rename page routes: /epd/swift → /epd/cortex
- Rename store: swift-store.ts → cortex-store.ts

Type Renames:
- SwiftIntent → CortexIntent
- SwiftStore → CortexStore
- useSwiftStore → useCortexStore
- SwiftContext → CortexContext
- useSwiftVoice → useCortexVoice

Documentation Updates (docs/intent/):
- Safety Net → Nudge (Layer 3 rename)
- SafetySuggestion → NudgeSuggestion
- evaluateSafetyNet → evaluateNudge
- SWIFT_* feature flags → CORTEX_*
- All path references updated to match new structure

Files affected: 47 files, ~700 lines changed

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

components/cortex/artifacts/artifact-tab.tsx

@@ -0,0 +1,63 @@
+'use client';
+
+/**
+ * Artifact Tab Component
+ *
+ * Tab voor een individueel artifact in de ArtifactContainer.
+ * Toont titel, close button, en active state.
+ *
+ * Epic: E4 (Artifact Area & Tabs)
+ * Story: E4.S1 (ArtifactContainer component)
+ */
+
+import { X } from 'lucide-react';
+import { cn } from '@/lib/utils';
+import type { Artifact } from '@/stores/cortex-store';
+
+interface ArtifactTabProps {
+  artifact: Artifact;
+  isActive: boolean;
+  onSelect: (id: string) => void;
+  onClose: (id: string) => void;
+}
+
+export function ArtifactTab({ artifact, isActive, onSelect, onClose }: ArtifactTabProps) {
+  return (
+    <div
+      className={cn(
+        'group flex items-center gap-2 px-4 py-2.5 border-r border-slate-200 cursor-pointer transition-colors',
+        'hover:bg-slate-50 min-w-[140px] max-w-[200px]',
+        isActive && 'bg-white border-b-2 border-b-amber-500'
+      )}
+      onClick={() => onSelect(artifact.id)}
+    >
+      {/* Tab title */}
+      <span
+        className={cn(
+          'flex-1 text-sm font-medium truncate',
+          isActive ? 'text-slate-900' : 'text-slate-600'
+        )}
+        title={artifact.title}
+      >
+        {artifact.title}
+      </span>
+
+      {/* Close button */}
+      <button
+        onClick={(e) => {
+          e.stopPropagation();
+          onClose(artifact.id);
+        }}
+        className={cn(
+          'p-0.5 rounded hover:bg-slate-200 text-slate-400 hover:text-slate-700 transition-colors',
+          'opacity-0 group-hover:opacity-100',
+          isActive && 'opacity-100'
+        )}
+        title="Sluiten"
+        aria-label={`Sluit ${artifact.title}`}
+      >
+        <X size={14} />
+      </button>
+    </div>
+  );
+}