fix(docs): surface work-product open failures with a toast

Clicking a Files & Deliverables row fired openWorkProduct and then
discarded the result with \`void\`. When the main process could not
resolve the target — archived work product, missing workspace root,
path outside the managed root, or \`shell.openPath\` reporting no
associated app for the file type — the renderer stayed silent and
the row looked like a dead button. The user had no way to know why
"clicking" did nothing.

Await the result in WorkProductRow and route non-ok responses through
addToast with tone="danger". The caller sees the underlying failure
(OPEN_PATH_FORBIDDEN / OPEN_PATH_FAILED / WORK_PRODUCT_NOT_FOUND /
the shell's own message) and can act on it. No backend change — the
handler already returned structured errors; this just stops dropping
them.

Typecheck and build:verify clean.

src/renderer/components/company-operations/DocumentCenter.tsx

@@ -3,6 +3,7 @@ import { FileText, FloppyDisk, NotePencil, Plus, Trash } from "../ui/icons";
 import type { AgentRecord, DocumentRecord, GoalRecord, ProjectRecord, WorkProductRecord } from "@shared/types";
 import { ActionButton, ConfirmDialog, EmptyState, InlineNotice, Input, ListFrame, ListRow, Modal, Select, StatusPill, TextArea } from "../ui";
 import { useT } from "../../i18n";
+import { useAppStore } from "../../state/store";
 import { documentTypeOptions, documentStatusOptions, splitTags, parseTags } from "./helpers";
 import { SectionHeader } from "./SectionHeader";
 import { NEW_ENTITY_ID } from "../../lib/constants";
@@ -66,6 +67,7 @@ function DocumentEditor({ companyId, agents, projects, goals, document, onSaved
 }
 
 function WorkProductRow({ product, companyId }: { product: WorkProductRecord; companyId: string }) {
+  const addToast = useAppStore((s) => s.addToast);
   const subtitle = [
     product.type.replaceAll("_", " "),
     product.provider,
@@ -76,9 +78,16 @@ function WorkProductRow({ product, companyId }: { product: WorkProductRecord; co
   // the main process can join it against the work product's workspace
   // root before handing off to the OS shell. Direct `openPath(externalId)`
   // used to flash a failure when the renderer tried to treat the relative
-  // path as absolute.
+  // path as absolute. Surface shell failures (no associated app, path
+  // outside managed root, workspace moved) as a toast so the click
+  // doesn't look like a dead button when the OS can't complete the open.
   const primaryAction = product.url || (product.provider === "filesystem" && product.externalId)
-    ? () => { void window.agentCompany.openWorkProduct({ companyId, id: product.id }); }
+    ? async () => {
+        const result = await window.agentCompany.openWorkProduct({ companyId, id: product.id });
+        if (!result.ok) {
+          addToast(`Couldn't open ${product.title}: ${result.error.message}`, "danger");
+        }
+      }
     : undefined;
   return (
     <ListRow onClick={primaryAction}>