Bug: Accented characters not stripped from branch name on the Create Branch page

### Current behavior
When clicking "Create branch" from a Jira issue, the branch name field on the creation page keeps accented characters from the issue summary (e.g. `PROJ-42-ajout-du-système-d-authentification`).

Interestingly, the git command suggested when clicking the arrow next to "Create branch" correctly strips accented characters (e.g. `git checkout -b PROJ-42-ajout-du-systeme-d-authentification`). The sanitization logic exists but is not applied consistently.

### Expected behavior
The branch name field on the Create Branch page should apply the same sanitization as the git command suggestion, transliterating accented characters to their ASCII equivalent.

### Impact
Branch names with accented characters cause downstream errors — for example, when using the Claude integration in GitHub, which fails to process branches containing non-ASCII characters.

This affects any team writing Jira issue titles in a non-English language (French, Spanish, German, etc.).

Start at the Create Branch page and compare how its branch name field is populated with the git command suggestion shown by the arrow. Trace where the existing sanitization logic is applied, then verify that the field transliterates accented characters to ASCII just as the suggested command does.

Written by the indexing model from the issue text.