CRITICAL REDESIGN REQUIRED. The current Tessera frontend is dark-mode-only and not user-friendly. Implement these changes:

## 1. LIGHT MODE AS DEFAULT
Rewrite the theme system. shadcn/ui supports light/dark via CSS variables.

- Remove forced `className="dark"` from HTML element in layout.tsx
- Add ThemeProvider (install next-themes: bun add next-themes)
- Light mode is DEFAULT. Dark mode via toggle.
- Use shadcn/ui's built-in CSS variable system (already in globals.css)

Light mode colors:
- Background: white for canvas, #f8f9fa for panels/sidebar
- Text: #1a1a2e primary, #4a4a6a secondary, #6b7280 tertiary
- Borders: #e5e7eb, Cards: white with shadow
- Accent: #5e6ad2 (works in both modes)

Dark mode (toggled): keep existing Linear-inspired dark theme

## 2. BETTER FONT
- Primary: 'Inter' from next/font/google with font-feature-settings: 'cv01' 1, 'ss03' 1 (geometric Linear-like character)
- Monospace: 'JetBrains Mono' for ticket IDs, code, config
- Headings: tighter letter-spacing (-0.02em)
- Body: 15px base, line-height 1.5

## 3. UX IMPROVEMENTS

### Ticket list (page.tsx):
- Inbox-like rows: padding, hover highlight, subtle left border on hover
- Add checkbox column for future batch actions
- Clicking row opens detail in split view: list stays on left, detail on right
- OR simplified: click opens slide-over Sheet from right showing detail
- "New Ticket" button: prominent with gradient background

### Ticket detail (tickets/[id]/page.tsx):
- Better conversation hierarchy: customer messages tinted, agent clearly differentiated
- Properties sidebar: group into Status/Assignment/Details sections with dividers
- Status dropdown: more prominent (most important action)

### Global:
- Smooth transitions (150ms ease) on hover states
- Border radius consistency (8px cards, 6px inputs)
- Sidebar collapse/expand with hamburger
- Breadcrumb navigation at top of detail pages
- Tooltips on icon buttons
- Split-view or sheet overlay for ticket detail from list

### Command palette:
- Ensure Cmd+K / Ctrl+K triggers it
- Add fuzzy ticket search
- Add quick actions

## 4. IMPLEMENTATION
- Read current files first
- Modify existing files, don't delete
- Preserve api.ts and types.ts
- Use next-themes for theme switching
- shadcn/ui CSS variables already in globals.css

## 5. VERIFY
- `cd web && bun run build` — zero TypeScript errors
- Both light and dark mode work
- Font has OpenType features applied
- Ticket list is inbox-like