Add Python REPL, instant deploy, Gist import, presentation mode, and CSS visual tools

- Python mode via Pyodide WASM runtime with stdout/stderr console integration
- Publish fiddles to clean /p/:slug URLs as standalone HTML pages
- Import code from GitHub Gist URLs with auto-detection of language/mode
- Presentation mode with slide management, fullscreen viewer, and keyboard nav
- Enable Monaco color decorators for inline CSS color pickers
- Extract reusable generateStandaloneHtml from export module

public/js/editors.js

@@ -33,6 +33,7 @@ const editorOpts = {
   autoClosingQuotes: 'always',
   autoSurround: 'languageDefined',
   bracketPairColorization: { enabled: true },
+  colorDecorators: true,
 };
 
 export const MODE_TABS = {
@@ -73,6 +74,10 @@ export const MODE_TABS = {
     { id: 'css', label: 'CSS', lang: 'css', ext: 'css' },
     { id: 'js', label: 'JavaScript', lang: 'javascript', ext: 'js' },
   ],
+  'python': [
+    { id: 'js', label: 'Python', lang: 'python', ext: 'py' },
+    { id: 'html', label: 'HTML', lang: 'html', ext: 'html' },
+  ],
 };
 
 // Map mode names to js_type values stored in DB
@@ -85,6 +90,7 @@ export const MODE_TO_JS_TYPE = {
   'svelte': 'svelte',
   'markdown': 'markdown',
   'wasm': 'wasm',
+  'python': 'python',
 };
 
 export const JS_TYPE_TO_MODE = Object.fromEntries(