Implementiere Projekt Design

src/plainui/jinja2.py

src/plainui/jinja2/plainui/components/list_projects.html.j2

src/plainui/jinja2/plainui/components/tagbox.html

src/plainui/jinja2/plainui/project.html.j2

src/plainui/styles/_grid.scss

src/plainui/urls.py

src/plainui/views/projects.py