[improvement] add usage of LocalStorage to history

[engylemure]

Added usage of the LocalStorage to save the current history into it, allowing the user to visualize the recently executed queries between page reloads.

[rlaiola]

Reference issue

#233

What does this implement/fix?

This PR implements persistent editor state and improves editor history handling by using LocalStorage, fixes cross-tab contamination of saved editor content/history, adds TTL and reload-detection for autosaved editor content, and ensures the language-change confirmation text is loaded from the JSON locale resources.

• Editor content persistence: The CodeMirror editor content is now saved to localStorage so the editor state is restored after a page reload. Saved content is stored as a JSON payload (e.g. { "content": "...", "savedAt": 169... }) which allows TTL-aware restores and safer upgrades.

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• TTL & reload/navigation behavior:

  • A contentTtlMs prop allows automatic expiration of autosaved content (so stale drafts are ignored). Default: no expiration.
  • Best-effort detection of a "hard reload" vs in-app navigation (isReloadNavigation()), plus props clearOnReload and clearOnNavigation, allow choosing whether to restore or start fresh when the user reloads or navigates away/back. Default: clearOnReload=false and clearOnNavigation=true.

  Before:

  clear on reload	clear on navigation

  After:

  restore on reload	clear on navigation

• Per-tab storage isolation (fix for cross-pollination):

  • Storage and history keys now use props.tab || props.mode (the logical editor tab id) instead of props.mode alone. This prevents saved content or history from one editor (e.g. Group Editor) being loaded into another (e.g. RelAlg, BagAlg).
  • History operations (load/append/clear) were updated to use the same tab-based key.

• LocalStorage-backed history:

  • Editor history (previous queries / snippets) is persisted to localStorage under a per-editor key. Helper functions (e.g. appendHistoryToStorage, loadHistoryFromStorage, clearHistoryFromStorage) are used to maintain a stable history with maximum size and to synchronize across tabs/windows via storage events.

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  • Clearing history is scoped by the same per-tab key so clearing one editor's history does not cause unexpected UI side effects.

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• i18n fix (missing localization key):

  • The confirmation text used by navigation.tsx (i18n.t('local.change')) was missing from the JSON locale files that i18n loads. This PR adds the local.change entry to the JSON locale bundles (e.g. src/locales/en.json, de.json, es.json, etc.) so localized confirmation messages display correctly.

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• Files (high-level)

  • Modified: src/calc2/components/editorBase.tsx
    • Added helpers for storage keys, TTL-aware load/save, reload detection, save-on-change hook, and updated history key usage.
    • Added props: contentTtlMs?: number, clearOnReload?: boolean, clearOnNavigation?: boolean.
    • Switched all editor storage/history operations to use props.tab || props.mode.
  • Reviewed / Updated: src/calc2/components/*Editor*.tsx (editor instantiations)
    • Ensure EditorBase is invoked with the appropriate tab prop if needed to isolate storage.
  • Modified: src/calc2/i18n.tsx (investigation) and updated locale payloads in src/locales/*.json
    • Added local.change to JSON locale files consumed by i18n (so i18n.t('local.change') returns a message).
  • Other: history helper functions used across editor components (load/append/clear) were wired to tab-based keys.

• Why this change?

  • Prevents surprising content loss or cross-pollination between different editor tabs.
  • Improves user experience by restoring in-progress edits after reloads (configurable).
  • Makes history persistent and scoped per logical editor, enabling consistent undo/history behavior across reloads and windows.
  • Fixes a visible bug where language-change confirmation text did not appear because it wasn't present in the JSON resources used by i18n.

• Reviewer notes / things to verify

  • Verify per-tab persistence:
    • Open two different editor tabs (e.g., RelAlg and Group), type different content into each, reload — ensure each editor restores its own content and doesn't show the other's content.
  • Verify clear-on-reload/navigation:
    • For all editor tabs clearOnReload=false and clearOnNavigation=true so content is preserved on reload and cleared on navigation.
  • Verify history persistence:
    • Add entries to history, reload, and confirm history is preserved per editor.
    • Use the "clear" action in history and confirm it only clears the history for the current editor tab.
  • Verify i18n fix:
    • Change language in UI and ensure window.confirm(i18n.t('local.change')) shows the localized string.

[rlaiola]

@engylemure I made some changes, give it a try!

Cheers.