Preferences in Settings and a home page the user chooses

Settings gets a Preferences section: theme, default Bible, the Bible new reading
plans start in, verse layout, commentary, text size, reading width, audio
narrator (the last three stay per device; text size and narrator are now
remembered). A Home page setting (My Studies, Bible Reader or Reading Plans)
decides where the app opens and where every Home button goes; already being
there means My Studies. Back arrows are labelled Home. Tests cover every page
leading back.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/hooks/usePrefsSync.js

@@ -5,7 +5,7 @@
 import { useCallback, useEffect, useRef } from 'react';
 import { getRemotePrefs, saveRemotePrefs } from '../syncService.js';
 
-export const PREF_KEYS = ['theme', 'translation', 'layout', 'commentarySource', 'position'];
+export const PREF_KEYS = ['theme', 'translation', 'layout', 'commentarySource', 'planTranslation', 'startPage', 'position'];
 const META_KEY = 'prefs-meta'; // { key: timestamp of the last change made on this device }
 const PUSH_DELAY_MS = 1000;
 const FOCUS_PULL_MIN_MS = 30_000;
@@ -16,7 +16,7 @@ const lsDel = (k) => { try { localStorage.removeItem(k); } catch { /* storage un
 const readMeta = () => { try { return JSON.parse(lsGet(META_KEY) || '{}'); } catch { return {}; } };
 const same = (a, b) => JSON.stringify(a) === JSON.stringify(b);
 
-// values: { theme, translation, layout, commentarySource, position: { book, chapter } }
+// values: { theme, translation, layout, commentarySource, planTranslation, startPage, position: { book, chapter } }
 // apply(key, value): puts a server value on screen and in localStorage
 // canApplyPosition(): false while the Reader is open, so a background sync never moves the page under you
 export function usePrefsSync({ values, apply, canApplyPosition = () => true }) {
@@ -58,7 +58,7 @@ export function usePrefsSync({ values, apply, canApplyPosition = () => true }) {
       window.clearTimeout(timerRef.current);
       timerRef.current = window.setTimeout(push, PUSH_DELAY_MS);
     }
-  }, [values.theme, values.translation, values.layout, values.commentarySource, values.position.book, values.position.chapter, push]); // eslint-disable-line react-hooks/exhaustive-deps
+  }, [values.theme, values.translation, values.layout, values.commentarySource, values.planTranslation, values.startPage, values.position.book, values.position.chapter, push]); // eslint-disable-line react-hooks/exhaustive-deps
 
   const pullServerPrefs = useCallback(async () => {
     enabledRef.current = true;