refactor(tests+frontend): one http_sink helper for the hook tests; apiErrorMessage replaces ten hand-rolled error-body parses; type X, import specifiers are not definitions (#2904, milestone 299 step 6)

tests/helpers.http_sink replaces three module-local _Sink handlers (the
write-path tests and the after-write test). ProjectView + SettingsView
parsed `(e as {body?:{error?}}).body?.error || fallback` by hand ten times
beside the apiErrorMessage canon (#2853) - all ten now call it. The
extractor (server + the hook awk mirror) no longer reads `import { type Foo }`
as a definition of Foo - that was the last "identical body" sym family.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/views/ProjectView.vue

@@ -1,7 +1,7 @@
 <script setup lang="ts">
 import { ref, computed, onMounted, watch } from "vue";
 import { useRoute, useRouter } from "vue-router";
-import { apiGet, apiPatch, apiDelete, apiPost, apiPut } from "@/api/client";
+import { apiGet, apiPatch, apiDelete, apiPost, apiPut, apiErrorMessage } from "@/api/client";
 import { useAuthStore } from "@/stores/auth";
 import { useToastStore } from "@/stores/toast";
 import { useTasksStore } from "@/stores/tasks";
@@ -543,8 +543,7 @@ async function saveForgePin() {
     if (project.value) project.value.forge_connection_id = forgePin.value;
     await loadCoverage();
   } catch (e) {
-    const body = (e as { body?: { error?: string } }).body;
-    toast.show(body?.error || "Failed to change the project's forge", "error");
+    toast.show(apiErrorMessage(e, "Failed to change the project's forge"), "error");
     forgePin.value = project.value?.forge_connection_id ?? null;
   } finally {
     savingForgePin.value = false;