Migrate admin configuration to jsonConfig with short-form i18n and legacy UI removal

[Copilot]

This PR migrates the adapter admin configuration from legacy Materialize HTML to jsonConfig while preserving all existing native config keys and data types (baseURL, pollJSON, pollIndex, validationMax). It also replaces words.js-based translations with short-form JSON i18n files and removes obsolete admin UI artifacts.

• Admin UI migration (jsonConfig)

  • Added admin/jsonConfig.json with equivalent fields and constraints from legacy UI.
  • Kept config schema unchanged to avoid any system.config data migration.
  • Added responsive layout sizing for all breakpoints (xs, sm, md, lg, xl).

• Adapter metadata update

  • Updated io-package.json to use:

    "adminUI": { "config": "json" }

• Translation migration

  • Replaced admin/words.js usage with short-form files:
    • admin/i18n/{de,en,es,fr,it,nl,pl,pt,ru,uk,zh-cn}.json
  • Translation keys align with all label/help texts defined in admin/jsonConfig.json.

• Legacy admin cleanup

  • Removed:
    • admin/index_m.html
    • admin/style.css
    • admin/words.js

• Documentation update

  • Added a WORK IN PROGRESS changelog entry in README.md for the jsonConfig migration.

• Example (new jsonConfig field definition)

  "pollJSON": {
    "type": "number",
    "label": "JSON polling interval (in seconds)",
    "help": "To read instantaneous power for all circuits. For reference, the device's built-in web interface polls every second.",
    "min": 1,
    "xs": 12,
    "sm": 12,
    "md": 6,
    "lg": 6,
    "xl": 6
  }

• • https://github.com/user-attachments/assets/cffbb2ff-9919-4914-83a3-bd39f00ddfd8