fix(search): use URL mode per-tab instead of shared localStorage

[ManthanNimodiya]

Summary

Fixes #11960

The search mode (?mode=everything / ?mode=ebooks) was being written to localStorage on every page load in ol.js:

if (urlParams.mode) {
    searchMode.write(urlParams.mode); // pollutes shared localStorage
}

Changes

• ol.js — Removed searchMode.write(urlParams.mode); passes urlParams down to SearchPage
• SearchBar.js — Added this._activeMode (URL mode takes priority, falls back to localStorage for homepage); replaced eager mode.sync with a deferred sync that only fires on explicit user radio interaction; composeSearchUrl gets an optional mode param; submitForm and renderAutocompletionResults use this._activeMode
• SearchPage.js — Accepts urlParams, stores _urlMode; updateModeInputs prefers _urlMode until user clicks a radio button, then hands back to localStorage naturally

Testing

1. Open two tabs: Tab A /search?q=python&mode=everything, Tab B /search?q=python&mode=ebooks
2. Each tab's radio must reflect its own URL — switching tabs must not affect the other
3. Submit from Tab A without touching the radio → result URL keeps mode=everything
4. Homepage (no ?mode= in URL): radio reflects localStorage fallback as before
5. Click radio → localStorage updates → next search on that tab uses the new value

[Copilot]

Pull request overview

Fixes a cross-tab state leak where mode (ebooks vs everything) could be overwritten via shared localStorage, causing mismatched radio state and inconsistent search URLs across tabs.

Changes:

• Stop writing ?mode= from the URL into shared localStorage on page load.
• Make SearchBar and SearchPage prefer URL-provided mode per-tab until the user explicitly changes the radio button, then allow localStorage to take over naturally.
• Extend composeSearchUrl to accept an optional mode override so submissions/autocomplete preserve per-tab mode.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
openlibrary/plugins/openlibrary/js/ol.js	Removes eager localStorage write on load; passes parsed URL params into SearchBar/SearchPage.
openlibrary/plugins/openlibrary/js/SearchPage.js	Adds per-tab URL-mode override logic for mode inputs until user interaction.
openlibrary/plugins/openlibrary/js/SearchBar.js	Tracks _activeMode (URL-first) and uses it for submits/autocomplete; defers mode.sync init firing.

[akramcodez]

LGTM