fix: allow dots in template URL parameter for version numbers (#7325)

## Summary
- Template names with dots (e.g.,
`templates-1_click_multiple_scene_angles-v1.0`) were being rejected by
the URL parameter validation
- Updated validation regex from `^[a-zA-Z0-9_-]+$` to
`^[a-zA-Z0-9_.-]+$` to allow dots for version numbers

## Test plan
- [x] Unit tests updated and passing
- [ ] Verify `?template=templates-1_click_multiple_scene_angles-v1.0`
loads correctly

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7325-fix-allow-dots-in-template-URL-parameter-for-version-numbers-2c56d73d365081d48c28f20d979846d7)
by [Unito](https://www.unito.io)

tests-ui/tests/platform/workflow/templates/composables/useTemplateUrlLoader.test.ts

@@ -187,7 +187,8 @@ describe('useTemplateUrlLoader', () => {
       'flux_simple',
       'flux-kontext-dev',
       'template123',
-      'My_Template-2'
+      'My_Template-2',
+      'templates-1_click_multiple_scene_angles-v1.0' // template with version number containing dot
     ]
 
     for (const template of validTemplates) {