feat(shared-ui): add navigation components and form elements

NEW COMPONENTS:

Navigation:
- NavLink: Reusable navigation link with active state, tooltips, badges
- Navbar: Horizontal top navigation with mobile menu support
- Sidebar: Vertical collapsible sidebar with theme toggle support

Form Elements:
- Select: Dropdown select with placeholder, error states
- Textarea: Multi-line input with auto-resize, character count
- Checkbox: Accessible checkbox with indeterminate state support

ENHANCED:
- Card: Added header/footer slots, interactive mode, filled variant

EXPORTS:
- NavItem, NavbarProps, SidebarProps, NavLinkProps types
- SelectOption type for Select component

All components use HSL CSS variables from shared-tailwind for
consistent theming across all apps.

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

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

packages/shared-ui/src/navigation/index.ts

@@ -0,0 +1,4 @@
+export { default as NavLink } from './NavLink.svelte';
+export { default as Navbar } from './Navbar.svelte';
+export { default as Sidebar } from './Sidebar.svelte';
+export type { NavItem, NavbarProps, SidebarProps, NavLinkProps } from './types';