feat(ux): 8 UX improvements — simpler home, advanced filters, phase tabs, 4-line rows

1. Simpler home page: only search box on landing, no filter dropdowns
2. Advanced filters: hidden behind toggle on results page, auto-open if active
3. Per-school phase rendering: each row renders based on its own data
4. Taller 4-line rows with context line (type, age range, denomination, gender)
5. Result-scoped filters: dropdown values reflect current search results
6. Fix blank filter values: exclude empty strings and "Not applicable"
7. Rankings: Primary/Secondary phase tabs with phase-specific metrics
8. Compare: Primary/Secondary tabs with school counts and phase metrics

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

nextjs-app/lib/types.ts

@@ -273,6 +273,14 @@ export interface PaginationInfo {
   total_pages: number;
 }
 
+export interface ResultFilters {
+  local_authorities: string[];
+  school_types: string[];
+  phases: string[];
+  genders: string[];
+  admissions_policies: string[];
+}
+
 export interface SchoolsResponse {
   schools: School[];
   page: number;
@@ -280,6 +288,7 @@ export interface SchoolsResponse {
   total: number;
   total_pages: number;
   search_mode?: 'name' | 'location';
+  result_filters?: ResultFilters;
   location_info?: {
     postcode: string;
     radius: number;
@@ -399,6 +408,7 @@ export interface RankingsParams {
   year?: number;
   local_authority?: string;
   limit?: number;
+  phase?: string;
 }
 
 export interface ComparisonParams {