build: update to angular 21

[chimurai]

Please check if the PR fulfills these requirements

• The commit messages follow these
  guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (check one with "x")

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other. Please describe: Upgrade to Angular v21

If it is a Bugfix, please describe the root cause and what could have been done to prevent it…

What is the current behavior? (You can link to an open issue here, add screenshots…)

Angular v20

What is the new behavior?

Angular v21

Does this PR introduce a breaking change? (check one with "x")

• Yes
• No

If this PR contains a breaking change, please describe the impact and migration
path for existing applications: …

Other information (if applicable):

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cc: @willmendesneto