feat: Brainstorm Topics with GSC + Issue #518 fixes + Blog Editor enhancements

Issue #518 - Subscription not updating after checkout:
- Fix stale closure in SubscriptionContext checkout polling (use subscriptionRef)
- Move checkout success polling from InitialRouteHandler into SubscriptionContext
- Remove redundant polling code from InitialRouteHandler
- Fix plan label: 'Free' instead of 'No Plan', proper capitalization
- Add plan refresh button in UserBadge
- Add 'View Costing Details' to UserBadge dropdown
- Rename 'ALwrity Podcast Maker' to 'Podcast Creator' across UI
- Clean subscription=success URL param after verification

Blog Writer WYSIWYG Editor enhancements:
- Per-section preview toggle (view/edit icons)
- Enhanced hover-based toolbar
- Circular SVG progress stats bar with detailed tooltip
- Research tool chips in stats bar footer
- Per-section TTS with useTextToSpeech hook (browser native)
- Full blog preview modal with print/PDF support
- PlayAllTTSButton: sequential playback with progress bar
- OnThisPageNav: floating sidebar with scroll tracking
- Section data attributes for scroll anchoring

GSC Brainstorm Topics feature:
- Backend: gsc_brainstorm_service.py (rule-based + LLM recommendations)
- Backend: POST /gsc/brainstorm endpoint with 3-word minimum validation
- Frontend: gscBrainstorm.ts API client
- Frontend: useGSCBrainstormConnection hook (popup OAuth, no /onboarding redirect)
- Frontend: useGSCBrainstorm hook (connect check + brainstorm call)
- Frontend: GSCBrainstormModal (3-tab results: Opportunities, Gaps, AI Recs)
- Frontend: BrainstormButton (visible at 3+ words, GSC connect overlay)
- Wire BrainstormButton into ManualResearchForm and ResearchAction
- Add blog_writer to gsc_auth router features for ALWRITY_ENABLED_FEATURES

frontend/src/components/BlogWriter/BlogWriterUtils/PhaseContent.tsx

@@ -7,6 +7,7 @@ import OutlineCtaBanner from './OutlineCtaBanner';
 import ManualResearchForm from '../ManualResearchForm';
 import ManualOutlineButton from '../ManualOutlineButton';
 import ManualContentButton from '../ManualContentButton';
+import PublishContent from './PublishContent';
 
 interface PhaseContentProps {
   currentPhase: string;
@@ -40,6 +41,8 @@ interface PhaseContentProps {
   onResearchComplete?: (research: any) => void; // Callback when research completes (for manual form)
   onOutlineGenerationStart?: (taskId: string) => void; // Callback when outline generation starts
   onContentGenerationStart?: (taskId: string) => void; // Callback when content generation starts
+  buildFullMarkdown?: () => string;
+  convertMarkdownToHTML?: (md: string) => string;
 }
 
 export const PhaseContent: React.FC<PhaseContentProps> = ({
@@ -74,6 +77,8 @@ export const PhaseContent: React.FC<PhaseContentProps> = ({
   onResearchComplete,
   onOutlineGenerationStart,
   onContentGenerationStart,
+  buildFullMarkdown,
+  convertMarkdownToHTML,
 }) => {
   return (
     <div style={{ display: 'flex', flex: 1, overflow: 'hidden' }}>
@@ -223,11 +228,14 @@ export const PhaseContent: React.FC<PhaseContentProps> = ({
           </div>
         )}
 
-        {currentPhase === 'publish' && seoAnalysis && seoMetadata && (
-          <div style={{ padding: '20px' }}>
-            <h3>Publish Your Blog</h3>
-            <p>Your blog is ready to publish!</p>
-          </div>
+        {currentPhase === 'publish' && buildFullMarkdown && convertMarkdownToHTML && (
+          <PublishContent
+            buildFullMarkdown={buildFullMarkdown}
+            convertMarkdownToHTML={convertMarkdownToHTML}
+            seoMetadata={seoMetadata}
+            seoAnalysis={seoAnalysis}
+            blogTitle={selectedTitle ?? undefined}
+          />
         )}
       </div>
     </div>