feat(ui): preserve application search bar content across navigation (#5655)

[somaz94]

Closes #5655

What

On the Applications list page, structured filters are persisted to view
preferences (localStorage), but the free-text search bar is only kept in the
URL query string. Navigating into an app and back via in-app navigation drops
the ?search= param, so the search box comes back empty while the filters
survive. The original issue asks for the search bar to be preserved the same
way the filters are.

Changes

• Add a search field to AppsListPreferences (default '', normalized on load).
• Persist the search text in ApplicationsListSearchBar.onChange alongside the
  existing URL update, mirroring how filters are stored.
• Seed the search bar from the resolved value, with precedence: URL query param
  (if present) > persisted preference > empty.

Validation

• pnpm lint (tsc --noEmit + eslint): clean.
• pnpm test (jest): 23 suites / 266 tests pass, including 3 new tests in
  view-preferences-service.test.ts covering the default, a persist + reload
  round-trip, and normalization of older stored preferences without search.

This is a UI-only change (the search box has no CLI equivalent).

---

Checklist:

• (c) this does not need to be in the release notes / tracked by existing issue Preserve application search bar content #5655 (good first issue, enhancement).
• The title states what changed and the related issue number.
• The title conforms to the PR title guidelines.
• I've included "Closes Preserve application search bar content #5655" in the description.
• CLI/UI parity — UI-only change; the search box has no CLI equivalent.
• I have signed off all my commits (DCO).
• I have written unit tests for my change.
• My build is green locally (lint + unit tests).
• I've added a description of why this PR is necessary.

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[codecov]

Bundle Report

Changes will increase total bundle size by 114 bytes (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
argo-cd-ui-array-push	11.15MB	114 bytes (0.0%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: argo-cd-ui-array-push

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
main.*.js	114 bytes	3.61MB	0.0%

[somaz94]

Rebased on latest master to clear the conflict.

The interesting part: master gained the regex search feature (searchRegex, the .* toggle, isInvalidRegex) after this branch was opened, and it touches the same ApplicationsListSearchBar / ApplicationsToolbar code as the search-preservation change here. So this wasn't a take-one-side resolution — I integrated both features:

• ApplicationsListSearchBar props now carry searchRegex and pref.
• The SearchBar onChange keeps the regex placeholder switching while also persisting the search text to view preferences (the actual fix here).
• The toolbar keeps the regex toggle button; the search bar just gains pref={pref}.
• URL search param still wins; it only falls back to the persisted preference when the param is absent, so regex and preservation don't fight over the value.

tsc --noEmit is clean for the changed files. Ready for another look.

[somaz94]

Open since June with no review. This preserves the application search bar content across navigation. Is that a change you would want in the UI? Happy to close if not, otherwise it is green and ready.