Refactor: Replace sidebar with horizontal navigation bar

- Remove sidebar and toggle functionality
- Add Bootstrap navbar with dropdown menus
- Move navigation to top between header and content
- Update menu rendering for Bootstrap dropdowns
- Clean up unused files (header.mustache, sidebar.mustache, sidebar.js)
- Add guide link with book icon in footer
- Simplify layout structure
- Remove duplicate code and fix syntax errors
- Add .gitignore for node_modules and other temp files

composer.lock

@@ -0,0 +1,72 @@
+{
+    "_readme": [
+        "This file locks the dependencies of your project to a known state",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
+        "This file is @generated automatically"
+    ],
+    "content-hash": "44b7b2c58a30151ae57314c84e2abdd5",
+    "packages": [
+        {
+            "name": "mustache/mustache",
+            "version": "v3.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/bobthecow/mustache.php.git",
+                "reference": "176b6b21d68516dd5107a63ab71b0050e518b7a4"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/bobthecow/mustache.php/zipball/176b6b21d68516dd5107a63ab71b0050e518b7a4",
+                "reference": "176b6b21d68516dd5107a63ab71b0050e518b7a4",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.6"
+            },
+            "require-dev": {
+                "friendsofphp/php-cs-fixer": "~2.19.3",
+                "yoast/phpunit-polyfills": "^2.0"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "Mustache\\": "src/"
+                },
+                "classmap": [
+                    "src/compat.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Justin Hileman",
+                    "email": "justin@justinhileman.info",
+                    "homepage": "http://justinhileman.com"
+                }
+            ],
+            "description": "A Mustache implementation in PHP.",
+            "homepage": "https://github.com/bobthecow/mustache.php",
+            "keywords": [
+                "mustache",
+                "templating"
+            ],
+            "support": {
+                "issues": "https://github.com/bobthecow/mustache.php/issues",
+                "source": "https://github.com/bobthecow/mustache.php/tree/v3.0.0"
+            },
+            "time": "2025-06-28T18:28:20+00:00"
+        }
+    ],
+    "packages-dev": [],
+    "aliases": [],
+    "minimum-stability": "stable",
+    "stability-flags": {},
+    "prefer-stable": false,
+    "prefer-lowest": false,
+    "platform": {},
+    "platform-dev": {},
+    "plugin-api-version": "2.9.0"
+}