Add screenshot capture script for documentation

- Capture main UI pages (Encode, Decode, Generate, Tools, About)
- Capture auth pages (Login, Setup, Account, Recover)
- Auto-convert PNG to WebP for smaller file sizes
- Update .gitignore to track this script

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

scripts/screenshots.sh

@@ -0,0 +1,93 @@
+#!/bin/bash
+# Capture Web UI screenshots for documentation
+# Requires: chromium, imagemagick
+# Usage: ./scripts/screenshots.sh [base_url]
+#
+# Modes:
+#   Default (auth disabled): Captures main UI pages
+#   With auth: Also captures login/setup/account pages
+#
+# Start server with: STEGASOO_AUTH_ENABLED=false python frontends/web/app.py
+
+set -e
+
+BASE_URL="${1:-http://localhost:5000}"
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+PROJECT_DIR="$(dirname "$SCRIPT_DIR")"
+OUTPUT_DIR="$PROJECT_DIR/data"
+WINDOW_SIZE="1280,900"
+
+echo "╔══════════════════════════════════════════╗"
+echo "║     Stegasoo Screenshot Capture          ║"
+echo "╚══════════════════════════════════════════╝"
+echo ""
+echo "Base URL: $BASE_URL"
+echo "Output:   $OUTPUT_DIR"
+echo ""
+
+# Check dependencies
+for cmd in chromium magick curl; do
+    if ! command -v "$cmd" &> /dev/null; then
+        echo "Error: $cmd not found"
+        exit 1
+    fi
+done
+
+# Check if server is running
+if ! curl -s "$BASE_URL" > /dev/null 2>&1; then
+    echo "Error: Server not responding at $BASE_URL"
+    echo "Start with: STEGASOO_AUTH_ENABLED=false python frontends/web/app.py"
+    exit 1
+fi
+
+# Capture a single screenshot
+capture() {
+    local name="$1"
+    local route="$2"
+    local url="$BASE_URL$route"
+
+    printf "  %-20s <- %s\n" "$name" "$route"
+    chromium --headless --screenshot="$OUTPUT_DIR/$name.png" \
+        --window-size="$WINDOW_SIZE" --hide-scrollbars \
+        --disable-gpu --no-sandbox \
+        "$url" 2>/dev/null
+}
+
+echo "Capturing main pages..."
+echo ""
+
+# Core pages (always capture)
+capture "WebUI"          "/"
+capture "WebUI_Encode"   "/encode"
+capture "WebUI_Decode"   "/decode"
+capture "WebUI_Generate" "/generate"
+capture "WebUI_Tools"    "/tools"
+capture "WebUI_About"    "/about"
+
+echo ""
+echo "Capturing auth pages..."
+echo ""
+
+# Auth pages (may redirect if auth disabled, that's OK)
+capture "WebUI_Login"    "/login"
+capture "WebUI_Setup"    "/setup"
+capture "WebUI_Account"  "/account"
+capture "WebUI_Recover"  "/recover"
+
+echo ""
+echo "Converting to webp..."
+echo ""
+
+for png in "$OUTPUT_DIR"/WebUI*.png; do
+    [ -f "$png" ] || continue
+    name=$(basename "$png" .png)
+    printf "  %-20s -> %s.webp\n" "$name.png" "$name"
+    magick "$png" -quality 85 "$OUTPUT_DIR/$name.webp"
+    rm -f "$png"
+done
+
+echo ""
+echo "Done! Screenshots:"
+echo ""
+ls -lh "$OUTPUT_DIR"/WebUI*.webp 2>/dev/null | awk '{print "  " $NF " (" $5 ")"}'
+echo ""