fix(workflow): repair always-skipped 'Replace repo owner' if-syntax

[marksverdhei]

Bug

```yaml

• name: Replace repo owner
  if: ${{ github.event.repository.owner.login }} != marksverdhei
  ```

This mixes `${{ }}` pre-substitution with a bare-text right-hand side. GHA evaluates the entire `if` value as an expression after substitution:

1. `${{ github.event.repository.owner.login }}` is substituted → e.g. `someuser`
2. The literal becomes: `someuser != marksverdhei`
3. GHA parses that as an expression. Both `someuser` and `marksverdhei` are unquoted identifiers → resolved as undefined context refs (both `null`)
4. `null != null` is `false`
5. Step always skipped

Effect: every new repo created from this template kept its `marksverdhei` references unreplaced. The bug never bit Markus's own usage of the template (other workflows would have caught it cosmetically) but is wrong for anyone else cloning the template — and silently so.

Fix

```yaml

• name: Replace repo owner
  if: github.event.repository.owner.login != 'marksverdhei'
  ```

Move the comparison entirely inside one expression scope. The quoted literal and the property reference now share the same evaluator, and the step runs whenever the owner isn't `marksverdhei` (matching the intent in the inline comment).

Why no test

This is a CI workflow — no local-runnable test suite to add to. The next time a non-marksverdhei user (real or test) clones from this template, the step will run and `marksverdhei` references will be replaced as documented.