UX: Complete Add Keywords and Sites Management detailed improvements

ADD KEYWORDS PAGE:
- Sector selection banner: 'Select a Sector to Add Keywords' → 'Choose a Topic Area First'
- Description: Updated to be more conversational and helpful
- Changed: 'Please select a sector from the dropdown above to enable adding keywords to your workflow. Keywords must be added to a specific sector.'
- To: 'Pick a topic area first, then add keywords - You need to choose what you're writing about before adding search terms to target'

SITES MANAGEMENT PAGE:
- Filter labels made more conversational:
- 'All Types' → 'Show All Types'
- 'All Hosting' → 'Show All Hosting'
- 'All Status' → 'Show All Status'

These changes complete the detailed text improvements from Sections 2 and 3 of the UX plan.

frontend/src/pages/Setup/IndustriesSectorsKeywords.tsx

@@ -662,10 +662,10 @@ export default function IndustriesSectorsKeywords() {
               </div>
               <div className="flex-1">
                 <h3 className="text-sm font-medium text-blue-900 dark:text-blue-200">
-                  Select a Sector to Add Keywords
+                  Choose a Topic Area First
                 </h3>
                 <p className="mt-1 text-sm text-blue-700 dark:text-blue-300">
-                  Please select a sector from the dropdown above to enable adding keywords to your workflow. Keywords must be added to a specific sector.
+                  Pick a topic area first, then add keywords - You need to choose what you're writing about before adding search terms to target
                 </p>
               </div>
             </div>