feat(feedback): Add content improvement feedback system

Frontend (frontend/app.js):

- Add textarea for improvement feedback

- Add submit button with loading state

- Handle API response and display improved content

Backend (backend/copywriter.py):

- Add improve_copy() method using Cohere API

- Integrate retry mechanism for API calls

Backend (backend/main.py):

- Add /improve-content POST endpoint

- Implement error handling and return improved content with metadata

Testing:

- Verified feedback submission flow

- Confirmed improved content generation

- Tested error scenarios and loading states

frontend/index.html

@@ -48,7 +48,7 @@
                 <div class="generation-form">
                     <div class="form-group">
                         <label for="prompt">What would you like to create?</label>
-                        <textarea id="prompt" placeholder="e.g., Write a social media post for our new coaching program launch" rows="4"></textarea>
+                        <textarea id="prompt" placeholder="e.g., Generate an email campaign for a product launch" rows="4"></textarea>
                     </div>
 
                     <div class="form-row">
@@ -84,12 +84,12 @@
 
                     <div class="form-group checkbox-group">
                         <label class="checkbox">
-                            <input type="checkbox" id="include-cta" checked>
+                            <input type="checkbox" id="include-cta" unchecked>
                             <span class="checkmark"></span>
                             Include Call to Action
                         </label>
                         <label class="checkbox">
-                            <input type="checkbox" id="reference-similar" checked>
+                            <input type="checkbox" id="reference-similar" unchecked>
                             <span class="checkmark"></span>
                             Reference Similar Content
                         </label>