refactor: remove dead code identified by knip

Delete unused Fab component (superseded by QuickAddFab), unused server
actions and queries (listDashboards, reorderDashboards, deleteCareLog,
canAccessContainer, getOverduePlants, getCareDueSoon, addItemToDefaultList,
reorderItems, getOrCreateDefaultList), unused helpers (getCurrentUser,
BrandWordmark, TopbarSpacer, DEV_LOGIN_COOKIE, no-arg ensureDefault*
wrappers, addListItem re-export), and drop export keyword from five
internal-only functions.

Verified with typecheck, eslint, and production build after each removal.

src/components/brand-mark.tsx

@@ -21,12 +21,3 @@ export function BrandMark({ size = "md", className }: { size?: "sm" | "md"; clas
     </span>
   );
 }
-
-export function BrandWordmark({ className }: { className?: string }) {
-  return (
-    <span className={cn("brand", className)}>
-      <BrandMark />
-      <span className="brand-name">famapp</span>
-    </span>
-  );
-}

src/components/fab.tsx

@@ -1,14 +0,0 @@
-"use client";
-
-import { useQuickAdd } from "@/components/quick-add-provider";
-import { NavIcon } from "@/components/nav-icon";
-
-export function Fab() {
-  const { openSheet } = useQuickAdd();
-
-  return (
-    <button type="button" className="fab" aria-label="Quick add" onClick={openSheet}>
-      <NavIcon name="plus" className="size-6" strokeWidth={2.4} />
-    </button>
-  );
-}

src/components/settings-section.tsx

@@ -17,7 +17,7 @@ const SECTIONS = [
 
 export type SectionId = (typeof SECTIONS)[number]["id"];
 
-export function SettingsSidebar({ active }: { active: SectionId }) {
+function SettingsSidebar({ active }: { active: SectionId }) {
   const router = useRouter();
   const pathname = usePathname();
 
@@ -78,7 +78,7 @@ function SectionHashSync({ pathname }: { pathname: string | null }) {
   return null;
 }
 
-export function SettingsTabsMobile({ active }: { active: SectionId }) {
+function SettingsTabsMobile({ active }: { active: SectionId }) {
   const router = useRouter();
   return (
     <div className="grid grid-cols-2 gap-1.5 mb-1">

src/components/topbar.tsx

@@ -6,7 +6,6 @@ import { NotificationBell } from "@/components/notification-bell";
 import { TopbarSearch } from "@/components/topbar-search";
 import { TopbarTitle } from "@/components/topbar-title";
 import { TopbarNewButton } from "@/components/topbar-new-button";
-import { NavIcon } from "@/components/nav-icon";
 
 async function getNotifications(userId: string) {
   const rows = await db
@@ -78,14 +77,3 @@ export async function Topbar() {
     </div>
   );
 }
-
-export function TopbarSpacer() {
-  return (
-    <div className="topbar">
-      <h1 className="serif">famapp</h1>
-      <div className="topbar-actions">
-        <NavIcon name="bell" className="size-4 text-[var(--ink-mute)]" />
-      </div>
-    </div>
-  );
-}