feat: added responsive capabilities for tables, buttons, forms, form …

[stajilov]

• Rebuilt the Bootstrap 4 list/filter/form stack for responsive behavior: filters render in flex cards, list tables emit data-label attributes, pagination hides extra items on xs screens, and the search bar/tab row flex-wraps with a fluid search control so the “List,” “Create,” “Add Filter,” and search UI stay usable on mobile. Key files: flask_admin/static/admin/css/bootstrap4/admin.css, flask_admin/static/admin/js/bs4_filters.js, flask_admin/templates/bootstrap4/admin/model/list.html, and flask_admin/templates/bootstrap4/admin/model/layout.html.
• Modernized form rendering and submit buttons: fields now use a Bootstrap grid (rows/columns) and the submit button row flexes/stacks on small screens to keep Save/Cancel reachable, while offsets remain on medium+ (flask_admin/templates/bootstrap4/admin/lib.html plus .submit-row styles).
• Added pagination-ready seed data to the Peewee example (50 posts, 20 users) so the list view’s responsive paging/card layout can be exercised locally (examples/peewee_simple/main.py).
• Added CSS helpers ensuring the .nav-tabs controls, responsive search form, and filter cards behave across breakpoints.

Testing

• uv run pytest fails locally because PostgreSQL/Mongo/S3/Azure services are unavailable in this environment; no automated UI/responsive tests exist yet.

[ElLorans]

Thanks for your work!
You can run make test-in-docker or make tox-in-docker to test locally. Can you add some screenshots to this PR?

[stajilov]

fig 1. Responsive form fig 2. Responsive list

• updated the PR, verified selectors in tests

[stajilov]

tests ran OK now

• modified peewee example to feature more records so it's possible to see pagination