UX Text Improvements: Thinker Module Pages

- Updated page titles to be more descriptive:
  * Prompts: 'AI Prompts Management' → 'Customize Your AI Writer'
  * AuthorProfiles: 'Author Profiles' → 'Choose Your Writing Voice'
  * Strategies: 'Content Strategies' → 'Your Content Strategies'
  * ImageTesting: 'Image Testing' → 'Test Your Image Generator'
  * Dashboard: 'Thinker Dashboard' → 'Your AI Configuration Dashboard'

- Updated navigation tab labels across all Thinker pages:
  * 'Prompts' → 'AI Instructions'
  * 'Author Profiles' → 'Writing Voices'
  * 'Strategies' → 'Content Strategies'
  * 'Image Testing' stays the same

- Updated Prompts page section titles:
  * 'Planner Prompts' → 'Keyword & Topic Instructions'
  * 'Writer Prompts' → 'Article Writing Instructions'
  * Updated descriptions to be more conversational

Part of comprehensive UX text improvement initiative.

frontend/src/pages/Thinker/Dashboard.tsx

@@ -147,7 +147,7 @@ export default function ThinkerDashboard() {
   return (
     <>
       <PageMeta title="Thinker Dashboard - IGNY8" description="Strategic OS and thinking engine" />
-      <PageHeader title="Thinker Dashboard" />
+      <PageHeader title="Your AI Configuration Dashboard" />
 
       <div className="space-y-6">
         {/* Key Metrics */}