feat(alerting): server-side state+severity filters, ButtonGroup filter UI

Backend: `GET /environments/{envSlug}/alerts` now accepts optional multi-value
`state=…` and `severity=…` query params. Filters are pushed down to
PostgresAlertInstanceRepository, which appends `AND state::text = ANY(?)` /
`AND severity::text = ANY(?)` to the inbox query (null/empty = no filter).

`AlertInstanceRepository.listForInbox` gained a 7-arg overload; the old 5-arg
form is preserved as a default delegate so existing callers (evaluator,
AlertingFullLifecycleIT, PostgresAlertInstanceRepositoryIT) compile unchanged.
`InAppInboxQuery.listInbox` also has a new filtered overload.

UI: InboxPage severity filter migrated from `SegmentedTabs` (single-select,
no color cues) to `ButtonGroup` (multi-select with severity-coloured dots),
matching the topnavbar status-filter pattern. `useAlerts` forwards the
filters as query params and cache-keys on the filter tuple so each combo
is independently cached.

Unit + hook tests updated to the new contract (5 UI tests + 8 Java unit
tests passing). OpenAPI types regenerated from the fresh local backend.

cameleer-server-app/src/main/java/com/cameleer/server/app/alerting/controller/AlertController.java

@@ -8,6 +8,8 @@ import com.cameleer.server.app.web.EnvPath;
 import com.cameleer.server.core.alerting.AlertInstance;
 import com.cameleer.server.core.alerting.AlertInstanceRepository;
 import com.cameleer.server.core.alerting.AlertReadRepository;
+import com.cameleer.server.core.alerting.AlertSeverity;
+import com.cameleer.server.core.alerting.AlertState;
 import com.cameleer.server.core.runtime.Environment;
 import io.swagger.v3.oas.annotations.tags.Tag;
 import jakarta.validation.Valid;
@@ -54,10 +56,12 @@ public class AlertController {
     @GetMapping
     public List<AlertDto> list(
             @EnvPath Environment env,
-            @RequestParam(defaultValue = "50") int limit) {
+            @RequestParam(defaultValue = "50") int limit,
+            @RequestParam(required = false) List<AlertState> state,
+            @RequestParam(required = false) List<AlertSeverity> severity) {
         String userId = currentUserId();
         int effectiveLimit = Math.min(limit, 200);
-        return inboxQuery.listInbox(env.id(), userId, effectiveLimit)
+        return inboxQuery.listInbox(env.id(), userId, state, severity, effectiveLimit)
                 .stream().map(AlertDto::from).toList();
     }
 

cameleer-server-app/src/main/java/com/cameleer/server/app/alerting/notify/InAppInboxQuery.java

@@ -4,6 +4,7 @@ import com.cameleer.server.app.alerting.dto.UnreadCountResponse;
 import com.cameleer.server.core.alerting.AlertInstance;
 import com.cameleer.server.core.alerting.AlertInstanceRepository;
 import com.cameleer.server.core.alerting.AlertSeverity;
+import com.cameleer.server.core.alerting.AlertState;
 import com.cameleer.server.core.rbac.RbacService;
 import org.springframework.stereotype.Component;
 
@@ -54,9 +55,22 @@ public class InAppInboxQuery {
      * or target a role the user holds. Empty target lists mean "broadcast to all".
      */
     public List<AlertInstance> listInbox(UUID envId, String userId, int limit) {
+        return listInbox(envId, userId, null, null, limit);
+    }
+
+    /**
+     * Filtered variant of {@link #listInbox(UUID, String, int)}: optional {@code states}
+     * and {@code severities} narrow the result set. {@code null} or empty lists mean
+     * "no filter on that dimension".
+     */
+    public List<AlertInstance> listInbox(UUID envId,
+                                         String userId,
+                                         List<AlertState> states,
+                                         List<AlertSeverity> severities,
+                                         int limit) {
         List<String> groupIds   = resolveGroupIds(userId);
         List<String> roleNames  = resolveRoleNames(userId);
-        return instanceRepo.listForInbox(envId, groupIds, userId, roleNames, limit);
+        return instanceRepo.listForInbox(envId, groupIds, userId, roleNames, states, severities, limit);
     }
 
     /**

cameleer-server-app/src/main/java/com/cameleer/server/app/alerting/storage/PostgresAlertInstanceRepository.java

@@ -98,12 +98,14 @@ public class PostgresAlertInstanceRepository implements AlertInstanceRepository
                                             List<String> userGroupIdFilter,
                                             String userId,
                                             List<String> userRoleNames,
+                                            List<AlertState> states,
+                                            List<AlertSeverity> severities,
                                             int limit) {
         // Build arrays for group UUIDs and role names
         Array groupArray = toUuidArrayFromStrings(userGroupIdFilter);
         Array roleArray  = toTextArray(userRoleNames);
 
-        String sql = """
+        StringBuilder sql = new StringBuilder("""
             SELECT * FROM alert_instances
              WHERE environment_id = ?
                AND (
@@ -111,10 +113,24 @@ public class PostgresAlertInstanceRepository implements AlertInstanceRepository
                    OR target_group_ids && ?
                    OR target_role_names && ?
                )
-             ORDER BY fired_at DESC
-             LIMIT ?
-            """;
-        return jdbc.query(sql, rowMapper(), environmentId, userId, groupArray, roleArray, limit);
+            """);
+        List<Object> args = new ArrayList<>(List.of(environmentId, userId, groupArray, roleArray));
+
+        if (states != null && !states.isEmpty()) {
+            Array stateArray = toTextArray(states.stream().map(Enum::name).toList());
+            sql.append(" AND state::text = ANY(?)");
+            args.add(stateArray);
+        }
+        if (severities != null && !severities.isEmpty()) {
+            Array severityArray = toTextArray(severities.stream().map(Enum::name).toList());
+            sql.append(" AND severity::text = ANY(?)");
+            args.add(severityArray);
+        }
+
+        sql.append(" ORDER BY fired_at DESC LIMIT ?");
+        args.add(limit);
+
+        return jdbc.query(sql.toString(), rowMapper(), args.toArray());
     }
 
     @Override