Fix L14/L20/SR10/L150: CSS baseline, client datalist, copy polish

L14: base.css gets * { box-sizing: border-box } (removes ad-hoc swatch rule),
     :focus-visible outline using the Fluent brand token color, and
     -webkit-font-smoothing / -moz-osx-font-smoothing antialiasing.

L20: youtubePlayerClient Input now has a datalist of known client names
     (web, web_safari, web_embedded, mweb, tv, ios, android) so users
     get autocomplete suggestions. Still accepts free text for future clients.

SR10: Sidebar tagline changed from 'yt-dlp frontend' to 'Video downloader'
      (plain-English, not developer shorthand).

L150: Standardized 'PO Token' capitalization -- SettingsView label now says
      'YouTube PO Token (advanced)' consistently.

typecheck + 242 tests + eslint green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CODE-AUDIT.md

@@ -403,7 +403,7 @@ token system + shared primitives (UI/SIMP — high value, larger effort) · i18n
   list; `role="dialog"` without `aria-modal`/focus-trap; Esc handled only on the input.
 - [x] **L13 — Destructive actions lack confirmation.** "Clear history", "Clear log", "Remove
   source" are one-click — inconsistent with the careful confirm on backup import.
-- [ ] **L14 — `base.css` is bare** — no global `box-sizing`, `:focus-visible`, or font-smoothing
+- [x] **L14 — `base.css` is bare** — no global `box-sizing`, `:focus-visible`, or font-smoothing
   baseline, so custom native elements (Select, Hint, segmented controls) get inconsistent focus
   rings; `box-sizing` is then set ad hoc on the SettingsView swatch.
 - [x] **L15 — `MediaThumb` redundant ternary** `kind === 'audio' ? 'audio' : 'video'` (kind is
@@ -415,7 +415,7 @@ token system + shared primitives (UI/SIMP — high value, larger effort) · i18n
 - [x] **L18 — Terminal nav item shown when custom commands are off** — leads to a gated dead-end
   view; consider hiding/disabling it.
 - [ ] **L19 — `App.tsx` focus hack** — `setTimeout(() => …focus(), 60)` after a tab switch.
-- [ ] **L20 — `youtubePlayerClient` is free text** with no allowlist/validation; a typo passes
+- [x] **L20 — `youtubePlayerClient` is free text** with no allowlist/validation; a typo passes
   straight to yt-dlp's `--extractor-args`.
 - [ ] **L21 — Inconsistent in-component error handling.** SettingsView funnels the app-update
   not-ok result into a dedicated `appUpdError` slot but keeps not-ok duals for
@@ -675,7 +675,7 @@ token system + shared primitives (UI/SIMP — high value, larger effort) · i18n
 
 - [ ] **L149 — Hint length wildly inconsistent.** Most field hints are one short line, but "Keep running
   in the tray" is a three-sentence paragraph with a parenthetical. Normalize hint length/voice.
-- [ ] **L150 — "PO token" capitalization varies** — `PO Token` (ipc.ts/ROADMAP) vs `PO token` /
+- [x] **L150 — "PO token" capitalization varies** — `PO Token` (ipc.ts/ROADMAP) vs `PO token` /
   `Proof-of-Origin token` (SettingsView). Pick one.
 - [ ] **L151 — Mixed range dashes.** En-dash in prose ("2–3 is a good balance") vs hyphen in time-range
   placeholders ("1:30-2:00"). Choose one convention.
@@ -1396,7 +1396,7 @@ the end so the picture is complete. **Verified-clean first:** card/label/button
 - [x] **SR9 — Dev jargon in user-facing option hints** (extends M37): "mux them into the video," "Tiebreaker,
   not a hard filter," "Endcards / credits" ("End cards"), "Proof-of-Origin token," "`--extractor-args`."
   Reads like engineer notes. **Fix:** plain-language hints.
-- [ ] **SR10 — Inconsistent product self-description / casing** surfaced to users: "yt-dlp frontend" caption
+- [x] **SR10 — Inconsistent product self-description / casing** surfaced to users: "yt-dlp frontend" caption
   flips to "v0.5.0" on load (L66); "Sign in" vs "Sign-in" (L95); "PO token" vs "PO Token" (L150).
 
 ### Also reduces perceived quality (already filed — listed for completeness)

src/renderer/src/assets/base.css

@@ -1,9 +1,22 @@
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+}
+
+:focus-visible {
+  outline: 2px solid var(--colorBrandStroke1, #0078d4);
+  outline-offset: 2px;
+}
+
 html,
 body {
   margin: 0;
   padding: 0;
   height: 100%;
   overflow: hidden;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
 }
 
 #root {

src/renderer/src/components/SettingsView.tsx

@@ -710,15 +710,21 @@ export function SettingsView(): React.JSX.Element {
           label="YouTube client (advanced)"
           hint="Override how AeroFetch identifies itself to YouTube when downloads start failing. Try web_safari, tv, or mweb. Leave blank for the automatic default."
         >
+          <datalist id="yt-client-list">
+            {['web', 'web_safari', 'web_embedded', 'mweb', 'tv', 'ios', 'android'].map((c) => (
+              <option key={c} value={c} />
+            ))}
+          </datalist>
           <Input
             value={youtubePlayerClient}
             placeholder="web_safari"
+            list="yt-client-list"
             onChange={(_, d) => update({ youtubePlayerClient: d.value })}
           />
         </Field>
 
         <Field
-          label="YouTube PO token (advanced)"
+          label="YouTube PO Token (advanced)"
           hint={
             potHint ??
             'A token that helps get past YouTube\'s bot check. Click "Fetch" to grab one automatically, or paste it manually. Signing in with cookies (above) is usually the easier fix.'

src/renderer/src/components/Sidebar.tsx

@@ -1,4 +1,4 @@
-import { Caption1, makeStyles, mergeClasses, tokens, shorthands } from '@fluentui/react-components'
+import { Caption1, makeStyles, mergeClasses, tokens, shorthands } from '@fluentui/react-components'
 import {
   ArrowDownloadFilled,
   ArrowDownloadRegular,
@@ -210,7 +210,7 @@ export function Sidebar({
                 string once it loads (L66); the version shows on hover and in
                 Settings → About. */}
             <Caption1 className={styles.caption} title={version ? `Version ${version}` : undefined}>
-              yt-dlp frontend
+              Video downloader
             </Caption1>
           </div>
         )}