Fix task status: 'complete' -> 'completed' for taskgraph compatibility

tasks/proxy/error-responses.md

@@ -1,7 +1,7 @@
 ---
 id: proxy/error-responses
 name: Implement proxy error responses with plain text bodies and correct status codes
-status: complete
+status: completed
 depends_on: [proxy/host-routing]
 scope: single
 risk: trivial

tasks/proxy/headers-and-forwarding.md

@@ -1,7 +1,7 @@
 ---
 id: proxy/headers-and-forwarding
 name: Implement proxy header injection, hop-by-hop removal, and request forwarding with hyper Client
-status: complete
+status: completed
 depends_on: [proxy/host-routing]
 scope: moderate
 risk: medium

tasks/proxy/host-routing.md

@@ -1,7 +1,7 @@
 ---
 id: proxy/host-routing
 name: Implement Host-based routing with global routing table from DynamicConfig
-status: complete
+status: completed
 depends_on: [config/dynamic-config]
 scope: narrow
 risk: low