Project name ending with dot (e.g., "sample.") lacks immediate validation warning; Finish triggers generic failure

Description
Creating a new project in the Mergin Maps QGIS plugin with a name ending in a dot (e.g., sample.) does not show the expected inline validation warning ("Incorrect project name!"). Instead, the Create New Mergin Maps Project dialog allows proceeding, and only after clicking Finish an error dialog appears: "Failed to create Mergin Maps project".

For comparison, using an invalid character like an asterisk (sample*) correctly shows the inline validation message. Behavior should be consistent across all invalid names, including trailing dot.

Environment
Staging/PROD

Application (+ app version, build, operating system)
QGIS versions:

• QGIS version: 3.40.5-Bratislava
• QGIS version: 3.22.10-Białowieża (minimum supported)

Mergin Maps plugin:

• Plugin version: 2025.4.0

My operating system:

• macOS: Sequoia 15.6

Steps to reproduce

1. Open QGIS with the Mergin Maps plugin.
2. Choose Create New Mergin Maps Project.
3. Enter a project name ending with a dot, e.g., sample..
4. Observe: No inline warning appears (unlike when using sample*).
5. Click Finish.
6. An error dialog appears: "Failed to create Mergin Maps project".

Actual results

• Names ending with . bypass inline validation and only fail at submission, returning a generic error.

Expected results

• Invalid project names (including trailing dot) should trigger the same inline validation warning ("Incorrect project name!") and block finishing until corrected.
• Screenshot of dialog with sample. (no inline warning).

Screenshots or logs

• Screenshot of the error dialog after clicking Finish.

Conclusion
Created by GitHub Copilot and supervised by a human test analyst.

Start by locating the Create New Mergin Maps Project dialog and the existing validation for invalid characters such as sample*. Reproduce the trailing-dot case, then verify that it shows the "Incorrect project name!" warning and prevents Finish instead of producing the generic failure dialog.