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>

app/(cortex)/epd/cortex/layout.tsx

@@ -0,0 +1,28 @@
+/**
+ * Cortex Layout
+ *
+ * Full-screen layout for Cortex Command Center.
+ * No sidebar - the entire screen is the Command Center.
+ */
+
+import type { ReactNode } from 'react';
+import { getUser } from '@/lib/auth/server';
+import { redirect } from 'next/navigation';
+
+interface CortexLayoutProps {
+  children: ReactNode;
+}
+
+export default async function CortexLayout({ children }: CortexLayoutProps) {
+  const user = await getUser();
+
+  if (!user) {
+    redirect('/login');
+  }
+
+  return (
+    <div className="min-h-screen bg-slate-50 flex flex-col">
+      {children}
+    </div>
+  );
+}