Add settings page, PIN manager, and auto-config

- New settings page at /settings (localhost-only) accessible via tray icon
- PIN manager with 6-digit codes, 5-min TTL, single-use
- API token uses secrets.token_urlsafe(32) for 256-bit entropy
- Config auto-creates config.yaml on first run with detected local IP
- Default PIN and token generated randomly on first startup
- Added pin_ttl setting (default 300s)
- Updated build_exe.py for onefile exe with settings assets bundled
- Added start.bat and start.sh for easy development startup

server/start.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+# PaperDash Server Startup Script
+# Creates venv if needed, installs dependencies, and starts the server
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR"
+
+# Create venv if it doesn't exist
+if [ ! -d "venv" ]; then
+    echo "Creating virtual environment..."
+    python3 -m venv venv
+fi
+
+# Activate venv
+source venv/bin/activate
+
+# Install dependencies
+echo "Installing dependencies..."
+pip install --upgrade pip
+pip install -r requirements.txt
+
+# Run the server
+echo "Starting PaperDash server..."
+echo "  Dashboard: http://localhost:8921"
+echo "  API docs:  http://localhost:8921/docs"
+echo ""
+echo "Set environment variables before starting:"
+echo "  DASHBOARD_PIN=1234"
+echo "  API_TOKEN=your-token"
+echo ""
+
+uvicorn main:app --host 0.0.0.0 --port 8921 --reload