Update OpenAI API key and enhance app functionality: Replace the OpenAI API key in the .env file for improved access. Refactor app.py to include error handling for missing API keys and implement dark mode functionality with session management. Update README.md to reflect the use of Tailwind CSS via CDN and document the Content Security Policy (CSP) adjustments. Enhance mindmap data loading with a new API endpoint for refreshing data, ensuring better user experience during database connection issues. Update styles and templates for improved UI consistency and responsiveness.

static/css/all.min.css

@@ -0,0 +1,27 @@
+/*
+ * Font Awesome 6.4.0
+ * 
+ * This is a placeholder file. For production, you should:
+ * 1. Download Font Awesome from https://fontawesome.com/download
+ * 2. Extract the downloaded package
+ * 3. Copy the 'css/all.min.css' file to this location
+ * 4. Copy the 'webfonts' folder to '/static/webfonts/'
+ *
+ * Alternatively, you can install via npm and copy the files:
+ * npm install @fortawesome/fontawesome-free
+ * cp -r node_modules/@fortawesome/fontawesome-free/css/all.min.css static/css/
+ * cp -r node_modules/@fortawesome/fontawesome-free/webfonts/ static/
+ */
+
+/* Placeholder styles for common Font Awesome icons */
+.fa, .fas, .far, .fab {
+  display: inline-block;
+  width: 1em;
+  text-align: center;
+}
+
+/* Warning message */
+body::before {
+  content: "Font Awesome CSS placeholder. Please replace with the actual file.";
+  display: none;
+}