Added localization

[Tokessa]

• Added a language selector button to the website (German and English available).
• Added functionality to close the settings menu when clicking outside of it.
• Updated the warning system to allow multiple warnings to be displayed simultaneously.

[Copilot]

Pull request overview

This PR introduces basic localization (German/English) to the RailBlocks UI and Blockly blocks, adds a language selector to the frontend, improves menu behavior (close on outside click), and refactors the warning system to support multiple concurrent warnings per block.

Changes:

• Add localization infrastructure (token tables, language selection, localized toolbox + UI labels).
• Add language selector UI (icon + menu) and outside-click handling for language/settings menus.
• Refactor workspace initialization (restore on reload) and update block warning logic to support multiple warning sources.

Reviewed changes

Copilot reviewed 10 out of 15 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
package.json	Adds ESLint-related dev dependencies.
package-lock.json	Introduces lockfile capturing dependency tree (incl. ESLint).
frontend/style.css	Adds shared button styling and language menu styles.
frontend/main.js	Applies stored language, localizes UI/toolbox, adds language menu logic, workspace save/restore, and multi-warning support.
frontend/localization.js	New localization helper that applies Blockly locale + custom RailBlocks messages and exposes label getters.
frontend/index.html	Adds language switcher UI and IDs used for localized label injection.
frontend/icons/language.svg	Adds language icon used by the new selector button.
frontend/dynamic_blocks.js	Replaces hardcoded English strings with localized Blockly.Msg.* tokens.
frontend/blocks.js	Switches JSON block texts/tooltips to %{BKY_...} tokens and generates toolbox from localized labels.
backend/tokens_en.js	Adds English token table for custom block strings/tooltips/warnings.
backend/tokens_de.js	Adds German token table for custom block strings/tooltips/warnings.
backend/executor/build_and_run.sh	Whitespace-only change.
backend/executor/build_and_run_deploy.sh	Whitespace-only change.
backend/backend.js	Removes an import (but currently breaks runtime due to exec still being used).
.gitignore	Adds ignore rules for Node/build artifacts and generated outputs.

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[Eddykasp]

we can target node 24 as the current LTS release