portal: add human-navigable service browser (GET /browse)

Registry: new GET /services/browse endpoint — paginated, no auth required,
returns ServiceBrowsePage (total, page, size, items). ServiceSummaryDto
extended with description, registrantName, registrantJurisdiction; lastCheckedAt
removed (not stored). ServiceBrowsePage added to apix-common as shared type.

Portal: ServiceBrowserResource at /browse (list + /browse/{id} detail);
ServiceRegistryClient for the new endpoints; PortalServiceView DTO for detail
deserialization; three Qute templates (browse, detail, error) in the existing
dark-theme design. Landing page links to /browse in the "Try it" section.

Architecture: registry stays pure JSON API; portal is the HTML layer over the
same data — two subdomains, no content negotiation required.

Co-Authored-By: Mira Rehfeld <noreply@anthropic.com>

apix-common/src/main/java/org/botstandards/apix/common/ServiceBrowsePage.java

@@ -0,0 +1,5 @@
+package org.botstandards.apix.common;
+
+import java.util.List;
+
+public record ServiceBrowsePage(long total, int page, int size, List<ServiceSummaryDto> items) {}

apix-common/src/main/java/org/botstandards/apix/common/ServiceSummaryDto.java

@@ -1,17 +1,18 @@
 package org.botstandards.apix.common;
 
-import java.time.Instant;
 import java.util.List;
 import java.util.UUID;
 
 public record ServiceSummaryDto(
         UUID id,
         String name,
+        String description,
         List<String> capabilities,
         OLevel oLevel,
         LivenessStatus livenessStatus,
         ServiceStage serviceStage,
         RegistryStatus registryStatus,
         String endpoint,
-        Instant lastCheckedAt
+        String registrantName,
+        String registrantJurisdiction
 ) {}