feat: migrate setup visibility from boolean to three-tier system

Replace isPublic boolean with visibility enum (private/link/public) across
the full stack. Add shares table to schema for future share link support.
Update all services, routes, schemas, hooks, components, and tests.

Plan: 32-01 (Setup Sharing System - Schema Migration)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/server/routes/account.ts

@@ -114,7 +114,7 @@ app.post("/delete", zValidator("json", deleteAccountSchema), async (c) => {
 		await tx
 			.update(setups)
 			.set({ userId: sentinel.id })
-			.where(and(eq(setups.userId, userId), eq(setups.isPublic, true)));
+			.where(and(eq(setups.userId, userId), eq(setups.visibility, "public")));
 
 		// 3. Get private setup IDs for cleanup
 		const privateSetups = await tx