fix(issues): skip agent wakeup when issue status is backlog

Agents were being woken immediately when an issue was created or
reassigned with status "backlog", defeating the purpose of backlog
as "not ready to work on yet" (issue #96).

Added `&& issue.status !== "backlog"` guard to both the CREATE and
PATCH wakeup paths, mirroring the existing done/cancelled suppression
pattern already present in the file.

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

server/src/routes/issues.ts

@@ -432,7 +432,7 @@ export function issueRoutes(db: Db, storage: StorageService) {
       details: { title: issue.title, identifier: issue.identifier },
     });
 
-    if (issue.assigneeAgentId) {
+    if (issue.assigneeAgentId && issue.status !== "backlog") {
       void heartbeat
         .wakeup(issue.assigneeAgentId, {
           source: "assignment",
@@ -566,7 +566,7 @@ export function issueRoutes(db: Db, storage: StorageService) {
     void (async () => {
       const wakeups = new Map<string, Parameters<typeof heartbeat.wakeup>[1]>();
 
-      if (assigneeChanged && issue.assigneeAgentId) {
+      if (assigneeChanged && issue.assigneeAgentId && issue.status !== "backlog") {
         wakeups.set(issue.assigneeAgentId, {
           source: "assignment",
           triggerDetail: "system",