chore(web): remove dead code surfaced by lint

Three mechanical lint warnings in the web package are resolved with
zero behavior change:

- web/src/app/(app)/notes/[noteId]/page.tsx — rename onTagsAccepted
  callback param to '_tags' to match the no-unused-vars allowlist
  (the param is intentionally unused; we trigger a re-save regardless).
- web/src/lib/feedback-client.ts — drop the unused PRODUCT_ID import.
- web/src/lib/notes-client.ts — delete the dead toWorkspaceSummary()
  helper. Workspace summaries are produced by listWorkspaceSummaries()
  on the backend response now; the local helper had no callers.

Web lint goes from 23 → 20 warnings. Remaining 20 are React-compiler
advisories about setState-in-effect patterns; those require careful
per-component refactoring (useReducer, derive-from-props, or
startTransition) and are tracked under Sprint D / Q1 tech debt rather
than fixed mechanically.

web/src/app/(app)/notes/[noteId]/page.tsx

@@ -274,7 +274,7 @@ export default function NoteDetailPage() {
             noteId={note.id}
             workspaceId={note.workspaceId}
             noteTags={note.tags}
-            onTagsAccepted={(tags) => void handleSave({ title: note.title, body: note.body }, { quiet: true })}
+            onTagsAccepted={(_tags) => void handleSave({ title: note.title, body: note.body }, { quiet: true })}
             onResultCreated={() => void getNoteDetail(note.id, note.workspaceId).then(setNote)}
           />
           <MetadataPanel note={note} />

web/src/lib/feedback-client.ts

@@ -1,7 +1,7 @@
 "use client";
 
 import { createFeedbackClient, type FeedbackClient } from "@bytelyst/feedback-client";
-import { PLATFORM_SERVICE_URL, PRODUCT_ID } from "@/lib/product-config";
+import { PLATFORM_SERVICE_URL } from "@/lib/product-config";
 import { getAccessToken } from "@/lib/api-helpers";
 
 let _client: FeedbackClient | null = null;

web/src/lib/notes-client.ts

@@ -46,22 +46,6 @@ function toNoteSummary(note: NoteDoc): NoteSummary {
   };
 }
 
-function toWorkspaceSummary(workspace: WorkspaceDoc, notes: NoteDoc[]): WorkspaceSummary {
-  const owner = workspace.members.find((member) => member.role === "owner")?.userId ?? workspace.updatedBy;
-  const noteCount = notes.filter((note) => note.workspaceId === workspace.id).length;
-
-  return {
-    id: workspace.id,
-    name: workspace.name,
-    description: workspace.description ?? "",
-    owner,
-    noteCount,
-    visibility: workspace.members.length > 1 ? "shared" : "private",
-    updatedAt: workspace.updatedAt,
-    tags: [],
-  };
-}
-
 function toNoteTask(task: NoteTaskDoc): NoteTask {
   return {
     id: task.id,