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/useBlogWriterPolling.ts

@@ -47,26 +47,50 @@ export const useBlogWriterPolling = ({
           });
           onSectionsUpdate(newSections);
           
-          // Cache the generated content (shared utility)
-          if (Object.keys(newSections).length > 0) {
-            const sectionIds = Object.keys(newSections);
-            blogWriterCache.cacheContent(newSections, sectionIds);
-            
-            // Auto-confirm content and navigate to SEO phase when content generation completes
-            // This happens when user clicks "Next:Confirm and generate content"
-            if (onContentConfirmed) {
-              onContentConfirmed();
-            }
-            if (navigateToPhase) {
-              navigateToPhase('seo');
-            }
+          // Auto-confirm content and navigate to SEO phase when content generation completes
+          // This happens when user clicks "Next:Confirm and generate content"
+          if (onContentConfirmed) {
+            onContentConfirmed();
           }
+          if (navigateToPhase) {
+            navigateToPhase('seo');
+          }
+
+          // Save to asset library (dedup by title is handled inside saveBlogToAssetLibrary)
+          // Backend also saves via save_and_track_text_content; this is a safety net / metadata update
+          (async () => {
+            try {
+              const { saveBlogToAssetLibrary } = await import('../../../services/blogWriterApi');
+              const totalWords = result.sections.reduce(
+                (sum: number, s: any) => sum + (s.wordCount || (s.content || '').split(/\s+/).length),
+                0
+              );
+              await saveBlogToAssetLibrary({
+                title: result.title || 'Untitled Blog',
+                blogType: 'medium',
+                wordCount: totalWords,
+                sectionCount: result.sections?.length,
+                model: result.model,
+                generationTimeMs: result.generation_time_ms,
+              });
+            } catch (assetError) {
+              console.error('[BlogWriter] Failed to save blog to asset library:', assetError);
+            }
+          })();
         }
       } catch (e) {
         console.error('Failed to apply medium generation result:', e);
       }
     },
-    onError: (err) => console.error('Medium generation failed:', err)
+    onError: (err: any) => {
+      console.error('Medium generation failed:', err);
+      const errMsg = (typeof err === 'string' ? err : (err?.message || err?.error || '')).toLowerCase();
+      if (errMsg.includes('insufficient_balance') || errMsg.includes('balance_not_enough') || (errMsg.includes('403') && errMsg.includes('balance'))) {
+        setTimeout(() => alert('Your API balance is insufficient. Please top up your account or switch to a different provider.'), 100);
+      } else if (errMsg.includes('no valid structured response')) {
+        setTimeout(() => alert('Content generation failed due to a provider error. This might be a temporary issue — please try again or switch providers.'), 100);
+      }
+    }
   });
 
   // Rewrite polling hook (used for blog rewrite operations)