welcome: username error handling (#75)

* username error handling welcome ui

* added short username check with separate error handling function

* nothing happaned here

* added username error handling, form saves info

* pull75 fixes

* pull75 fixes ui

* CSS change

* separate css for errors, added logic for several type of errors

* rename extractErrorMessage

* validation changes

* added validations in api

* changed rendering template, recives errors in JSON format

* rolled back schema and makefile in kratos

* changes in HTML

* combined kratos and manual validations

* fixed rendering and handling JSON error response

* rollback unused index.html

* minor fixes

* refactored the repeated logic of Errors into a separate function

* rollback

* refactor: group errors and form data together

* rollback picocss version

* use picocss 2.0.6

---------

Co-authored-by: Giorgi Lekveishvili <lekva@gl-mbp-m1-max.local>
diff --git a/core/installer/welcome/static/welcome.css b/core/installer/welcome/static/welcome.css
new file mode 100644
index 0000000..8aaa411
--- /dev/null
+++ b/core/installer/welcome/static/welcome.css
@@ -0,0 +1,18 @@
+.container {
+    position: relative; 
+}
+
+.error-message {
+    position: relative; 
+    left: 2px;
+    width: 100%;
+    margin-bottom: 1px;
+}
+
+.input-field {
+    margin-bottom: 14px;
+}
+
+.form-container {
+    margin-top: 0px; 
+}