backend/v2.1.1

This release includes a **license change** along with several improvements and fixes.

## License change
- The proprietary enterprise license in the /ee folder has been removed.
- Hanko Backend is now fully licensed under AGPLv3.

## Hanko Elements visual improvements
We’ve refined the look and feel of `<hanko-auth>`, `<hanko-login>`, and `<hanko-registration>`:
- Passcode views: user’s email address is now highlighted.
- Social SSO buttons:
  - Logos and text (e.g. “Sign in with Google”) are now centered.
  - Order updated: SSO buttons now appear first, with the passkey option listed last.
  - Passkey button icon removed for clearer visual separation from SSO options.
- Login/registration switch UI in <hanko-auth>:
  - Now centered at the bottom of the element (previously right-aligned).
  - Text and link split for clarity — the prompt (e.g. “Already got an account?”) is separate from the action link (e.g. “Sign in”), making the link more prominent.

## Hanko Elements `nonce` property added
- Added an optional nonce property to Hanko Elements.
- This enables a stricter Content Security Policy (CSP) without requiring `unsafe-inline`.
- Improves overall security posture by allowing Hanko Element's inline styling in combination with a stricter CSP when a valid nonce is provided.

## What's Changed
* Update LICENSE by @FlxMgdnz in https://github.com/teamhanko/hanko/pull/2184
* Delete backend/ee/README.md by @FlxMgdnz in https://github.com/teamhanko/hanko/pull/2183
* Delete backend/ee/LICENSE by @FlxMgdnz in https://github.com/teamhanko/hanko/pull/2182
* fix: add types for react 19 by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2067
* fix: oauth third party authentication with case insensitive email by @loeffert in https://github.com/teamhanko/hanko/pull/2196
* feat: support nonce for styles by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2197
* fix: update multiple backend dependencies by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2209
* Update en.ts by @FlxMgdnz in https://github.com/teamhanko/hanko/pull/2214
* fix user deletion when using mysql as DBMS by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2202
* fix: catch periodic session check error by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2204
* fix: take privacy setting into account when adding an email by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2208
* feat: highlight email address when logging in by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2216
* feat: change button order & content alignment by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2217
* feat: change flow switch UI by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2221
* fix: add all user properties to session by @FreddyDevelop in https://github.com/teamhanko/hanko/pull/2222


**Full Changelog**: https://github.com/teamhanko/hanko/compare/backend/v2.1.0...backend/v2.1.1