feat(search): add TagHint record for NL tag resolution API surface

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

backend/src/main/java/org/raddatz/familienarchiv/search/TagHint.java

@@ -0,0 +1,14 @@
+package org.raddatz.familienarchiv.search;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+import java.util.UUID;
+
+public record TagHint(
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+        UUID id,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+        String name,
+        String color
+) {
+}