Implement the following plan:

# Post-Writing UX Overhaul Plan

## Context
User wrote an anky and provided feedback about the writing experience. Several UX issues need fixing: landing page needs stronger copy, mobile writing is broken, navbar dropdown can't be clicked, share card overlay is annoying, writings page is ugly, and the app needs basic abuse prevention.

## Changes (in implementation order)

### 1. Navbar Dropdown Fix (CSS only)
### 2. Navbar Keyboard Navigation (JS + CSS)
### 3. Landing Page Copy + Simplification
### 4. Mobile Writing Responsiveness
### 5. Remove Share Card Overlay → Inline Share
### 6. Session Abuse Prevention (Backend)
### 7. Writings Page Redesign
### 8. Anonymous Anky Generation (verify)