feat(ui): nerd font icons on hard-defined list rows, graceful degrade

Tabs, Discover categories (replacing unused placeholder glyphs), Settings
sections, and the Feed 'Fetch More' row get Nerd Font glyphs (Font Awesome PUA
codepoints). When the terminal font isn't Nerd Font capable the glyphs render
nothing at all — no tofu, no layout gaps — via supportsNerdFonts() (env
allowlist + PODTUI_NERD_FONTS=1/0 override). Documented in README (Configuration
-> Fonts).

src/pages/Settings/SettingsPage.tsx

@@ -27,6 +27,7 @@ import {
 	type PaneId,
 } from "@/context/NavigationContext";
 import { on, off } from "@/utils/event-bus";
+import { NF_ICONS, supportsNerdFonts } from "@/utils/nerd-fonts";
 import type { KeybindActionName } from "@/context/KeybindContext";
 import type { SettingItem, SettingsSectionDef } from "./types";
 import { usePreferencesItems } from "./PreferencesPanel";
@@ -45,29 +46,38 @@ const SECTIONS: SettingsSectionDef[] = [
 		id: 0,
 		label: "Sync",
 		description: "Import/export subscriptions and sync status.",
+		icon: NF_ICONS.sync,
 	},
 	{
 		id: 1,
 		label: "Sources",
 		description: "Podcast search/RSS sources — add, enable, remove.",
+		icon: NF_ICONS.sources,
 	},
 	{
 		id: 2,
 		label: "Preferences",
 		description: "Theme, font, playback speed, explicit/auto-download.",
+		icon: NF_ICONS.preferences,
 	},
 	{
 		id: 3,
 		label: "Visualizer",
 		description: "Audio visualizer: bars, sensitivity, cutoffs.",
+		icon: NF_ICONS.visualizer,
 	},
 	{
 		id: 4,
 		label: "Downloads",
 		description: "Manage downloaded episodes — delete by show or individually.",
+		icon: NF_ICONS.downloads,
 	},
 ];
 
+// Static: detection never changes mid-session. Module-level because the Row
+// component below (a sibling module function) needs it too.
+const nerd = supportsNerdFonts();
+
 /** Resolve the items for a section id at render time. */
 function sectionItems(sectionId: number): SettingItem[] {
 	switch (sectionId) {
@@ -286,6 +296,7 @@ export function SettingsPage() {
 					{(section, index) => (
 						<Row
 							label={section.label}
+							icon={section.icon}
 							focused={index() === focusedSectionIdx()}
 							active={false}
 						/>
@@ -315,6 +326,7 @@ export function SettingsPage() {
 					{(section, index) => (
 						<Row
 							label={section.label}
+							icon={section.icon}
 							focused={index() === focusedSectionIdx()}
 							active={isActive()}
 							onMouseDown={() => {
@@ -407,6 +419,7 @@ function Row(props: {
 	focused: boolean;
 	active: boolean;
 	hint?: string;
+	icon?: string;
 	onMouseDown?: () => void;
 }) {
 	const { theme } = useTheme();
@@ -434,6 +447,7 @@ function Row(props: {
 			onMouseDown={props.onMouseDown}
 		>
 			<text fg={fg()}>{props.focused ? "❯" : " "}</text>
+			{props.icon && nerd && <text fg={fg()}>{props.icon}</text>}
 			<text fg={fg()}>{props.label}</text>
 			<Show when={props.value}>
 				<box flexGrow={1} />