feat(rename): complete searchSpace to workspace transition across frontend and backend

- Introduced a comprehensive specification for renaming `searchSpace` to `workspace` in `surfsense_web` and `surfsense_desktop`, ensuring all TypeScript identifiers, React props, and local data structures are updated.
- Implemented migration shims for persisted local state to prevent data loss during the transition.
- Updated observability metrics and IPC channels to reflect the new naming convention.
- Removed legacy `active-search-space` module and replaced it with `active-workspace` to maintain consistency.
- Ensured no behavioral changes or data loss for users during the renaming process.

surfsense_web/zero/schema/chat.ts

@@ -23,7 +23,7 @@ export const newChatMessageTable = table("new_chat_messages")
 export const newChatThreadTable = table("new_chat_threads")
 	.columns({
 		id: number(),
-		searchSpaceId: number().from("workspace_id"),
+		workspaceId: number().from("workspace_id"),
 	})
 	.primaryKey("id");