fix(backend): category/settings page fixes

[skerbis]

Part 2 of stacked PRs for #86.

Depends on: #87

Scope:

• Backend category/settings related fixes
• Page controller adjustments
• hide_categories focused fix layer
• Improved category/article selection UX (selectpicker + search)

Solved issues:

• Closes Linkmap Widget mit ID Eingabe #43

How and why:

• Linkmap Widget mit ID Eingabe #43 (Bedienung Link/Artikel-Auswahl):
  • How: Die Kategorie-/Artikelauswahl wurde als durchsuchbares Select (selectpicker + Live-Search) aktiviert und beim Seiten-Load robust initialisiert.
  • Why: Statt Klickpfaden durch Tiefe/Struktur ist die Auswahl schneller und präziser, insbesondere bei vielen Kategorien/Artikeln.
• Backend-Form-Logik im Kategorienbereich:
  • How: pageCategories() wird wieder zuverlässig auf rex:ready ausgeführt, sodass Feldsichtbarkeiten korrekt reagieren.
  • Why: Nach Entfernen von Inline-JS muss die zentrale Initialisierung greifen, sonst entsteht ein UX-Regressionsfehler.
• Output-Filter-Härtung bei hide_categories:
  • How: DOM-Parse abgesichert und Option-Entfernung ohne Live-NodeList-Mutationsproblem umgesetzt.
  • Why: Verhindert Edge-Case-Fehler bei fehlerhaftem HTML und stellt konsistente Filter-Ergebnisse sicher.

Base: stack/01-core
Next stacked PR: stack/03-docs

[Copilot]

Pull request overview

This PR is the second stacked step for #86 and focuses on backend adjustments around the category/settings pages and the hide_categories layer, aligning page controllers with the new namespaced class layout introduced in the core baseline.

Changes:

• Updates backend page entrypoints (pages/*) to reference the new namespaced page controller classes.
• Refines metainfo sidebar rendering to wrap the form in a PJAX container and hardens article lookups.
• Refactors category settings form inputs and tightens typing/handling across category-related backend helpers.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pages/settings.php	Imports the namespaced settings page controller class.
pages/content.metainfo.php	Avoids null dereference on missing articles and wraps metainfo form in a PJAX container.
pages/categories.php	Imports the namespaced categories page controller class.
lib/pages/page_settings.php	Adds namespace/imports and simplifies metainfo settings handling with backward-compatible config fallback.
lib/pages/page_categories.php	Adds namespace/imports, adds stricter typing, and refactors category/article selection UI.
lib/hide_categories.php	Adds namespace/imports, uses CSP nonces for injected scripts, and replaces DOM parsing approach for option removal.

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[skerbis]

Addressed Copilot review comments in follow-up commit 7f5b491:

• Restored backend initialization so pageCategories() runs again on rex:ready.
• Hardened option filtering in hide categories output filter:
  • Guarded HTMLDocument::createFromString() with try/catch fallback.
  • Avoided mutating a live NodeList during iteration by collecting nodes first and removing afterwards.

Also rebased top stack branch (stack/03-docs) onto updated stack/02-backend to keep stack consistency.