SaaS App Shell with Command Palette

Build a complete SaaS application shell — the outer frame/skeleton that wraps the entire product. Include:

1. **Top navigation bar (48px tall):**
   - Left: A workspace/account switcher (shows current workspace logo + name + ▾ dropdown. Clicking opens a dropdown listing all workspaces + "Create workspace" and "Sign out" at bottom).
   - Center: A fake search bar that reads "Search or jump to... ⌘K". Clicking it opens the command palette modal (see below).
   - Right: A notification bell (with red badge count), a "?" help button, and the current user avatar (opens a small popover with Profile, Settings, Changelog, Sign out).

2. **Left sidebar (240px, collapsible to 64px icon rail):**
   - A collapse toggle button at the top right of the sidebar.
   - Primary nav section: Home, Inbox, Projects, Tasks, Docs. Each item has an icon + label. Active state shows blue background.
   - A "Projects" section below with a list of 3-4 user-created projects (with colored dots and names) and a "+ New project" button.
   - A "Favorited" section with 2 items.
   - Bottom of sidebar: Upgrade plan nudge ("You're on Starter. Upgrade for more →"), and a help link.

3. **Main content area** — This is the slot where any page renders. Show a placeholder with a gray "Page content renders here" message to represent the slot.

4. **Command palette modal (⌘K):**
   - Appears as a centered modal with a blurred/dimmed backdrop.
   - Full-width search input at the top with a search icon and keyboard hint.
   - Results grouped by type: "Recent Pages", "Projects", "People", "Actions". Each result has an icon + title + shortcut hint on the right.
   - A footer row showing keyboard nav hints: ↑↓ to navigate, ↵ to open, ⎋ to close.

5. **Notification drawer:**
   - Slides in from the right as a panel (400px).
   - Header: "Notifications" + "Mark all read" link.
   - List of notification rows: avatar, name, action ("commented on"), target ("Task: Launch v2"), timestamp. Unread rows have a blue dot.

Use zinc-900 background for the sidebar and nav bar, white for main content. Clean icon set (Heroicons or Lucide style).

[TOP NAV BAR — 48px, zinc-900 bg]
  [Acme Inc ▾]          [🔍 Search or jump to...  ⌘K ]         [🔔 3] [?] [Avatar ▾]

[TWO-COLUMN — sidebar + main]

[SIDEBAR — 240px, zinc-900, collapsible → icon rail]
                                                        [← collapse]
  MAIN
  🏠 Home
  📥 Inbox              (2 unread badge)
  📁 Projects
  ✅ Tasks
  📄 Docs

  PROJECTS
  🔵 Acme Website
  🟢 Mobile App v2
  🔴 Q1 Marketing
  + New project

  FAVORITED
  ⭐ Design System
  ⭐ Sprint Board

  ──────────────────────
  ↑ You're on Starter.
  Upgrade for more →
  💬 Help & Support

[MAIN CONTENT — white, flex-1]
  ┌──────────────────────────────────────────────────────────┐
  │                                                          │
  │                                                          │
  │        [Page content renders here]                       │
  │                                                          │
  │                                                          │
  └──────────────────────────────────────────────────────────┘

[COMMAND PALETTE — modal, centered, dimmed backdrop]
  ┌────────────────────────────────────────────────────────┐
  │ [🔍 Search commands, pages, people...              ] ⎋ │
  │ ────────────────────────────────────────────────────── │
  │ RECENT PAGES                                           │
  │  📄 Design System               ↵                      │
  │  📁 Mobile App v2               ↵                      │
  │ PROJECTS                                               │
  │  🔵 Acme Website                ↵                      │
  │ ACTIONS                                                │
  │  ✨ Create new task             ⌘N                     │
  │  📩 Invite a teammate           ⌘I                     │
  │ ────────────────────────────────────────────────────── │
  │  ↑↓ navigate    ↵ open    ⎋ close                      │
  └────────────────────────────────────────────────────────┘

[NOTIFICATION DRAWER — right panel, 400px]
  Notifications                              Mark all read
  ─────────────────────────────────────────────────────────
  ● [Av] Sara commented on "Launch v2"        2 min ago
  ● [Av] Tom assigned you "Fix header bug"    1 hr ago
    [Av] Acme Website marked as complete      3 hrs ago
    [Av] New teammate joined workspace        Yesterday