refactor(features): extract HTML cleaning regex setup to standalone module

Extract ensureHtmlCleaningRegex into src/systems/features/htmlCleaning.js.
This module automatically imports the HTML cleaning regex script that
strips HTML tags from outgoing prompts to prevent formatting issues.

Passes SillyTavern imports (st_extension_settings, saveSettingsDebounced)
as parameters to avoid deep module import path issues.

- Create htmlCleaning.js with regex import logic
- Update index.js to import and use the new module with parameters
- Maintain backward compatibility with existing functionality

src/systems/features/htmlCleaning.js

@@ -0,0 +1,65 @@
+/**
+ * HTML Cleaning Module
+ * Automatically imports HTML cleaning regex to strip HTML tags from outgoing prompts
+ */
+
+/**
+ * Automatically imports the HTML cleaning regex script if it doesn't already exist.
+ * This regex removes HTML tags from outgoing prompts to prevent formatting issues.
+ * @param {Object} st_extension_settings - SillyTavern extension settings object
+ * @param {Function} saveSettingsDebounced - Function to save settings
+ */
+export async function ensureHtmlCleaningRegex(st_extension_settings, saveSettingsDebounced) {
+    try {
+        // Check if the HTML cleaning regex already exists
+        const scriptName = 'Clean HTML (From Outgoing Prompt)';
+        const existingScripts = st_extension_settings?.regex || [];
+        const alreadyExists = existingScripts.some(script => script.scriptName === scriptName);
+
+        if (alreadyExists) {
+            console.log('[RPG Companion] HTML cleaning regex already exists, skipping import');
+            return;
+        }
+
+        // Generate a UUID for the script
+        const uuidv4 = () => {
+            return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
+                const r = Math.random() * 16 | 0;
+                const v = c === 'x' ? r : (r & 0x3 | 0x8);
+                return v.toString(16);
+            });
+        };
+
+        // Create the regex script object based on the attached file
+        const regexScript = {
+            id: uuidv4(),
+            scriptName: scriptName,
+            findRegex: '/\\s?<(?!\\!--)(?:\"[^\"]*\"|\'[^\']*\'|[^\'\">])*>/g',
+            replaceString: '',
+            trimStrings: [],
+            placement: [2], // 2 = Input (affects outgoing prompt)
+            disabled: false,
+            markdownOnly: false,
+            promptOnly: true,
+            runOnEdit: true,
+            substituteRegex: 0,
+            minDepth: null,
+            maxDepth: null
+        };
+
+        // Add to global regex scripts
+        if (!Array.isArray(st_extension_settings.regex)) {
+            st_extension_settings.regex = [];
+        }
+
+        st_extension_settings.regex.push(regexScript);
+
+        // Save the changes using the already-imported function
+        saveSettingsDebounced();
+
+        console.log('[RPG Companion] ✅ HTML cleaning regex imported successfully');
+    } catch (error) {
+        console.error('[RPG Companion] Failed to import HTML cleaning regex:', error);
+        // Don't throw - this is a nice-to-have feature
+    }
+}