AP 019: Expand reusable component library ( FormField, Pagination, ConfirmDialog, EmptyState, Toast)

[pratigya245]

Adds a shared component library for the Admin Panel frontend under src/components/:

• FormField — label + input/select/textarea + hint/error, replaces hand-rolled field markup
• Pagination — reusable pager for table/list pages
• ConfirmDialog — confirmation prompt for destructive actions, built on the existing Modal
• EmptyState — placeholder for empty lists/tables
• Toast + ToastProvider/useToast — temporary notifications, wired into the root App layout

Demonstration: integrated FormField and Toast into the existing SMTP Settings page (AP-010) as a live example — all fields now use FormField, and save/test-email results surface via toast instead of inline banners. Behaviour is unchanged, verified locally against Mailpit.

Note: this branch is cut off pratigya245/feature/admin-smtp-config, so it includes the AP-010 password-validation fix from #464 (still pending review). Once #464 merges into main, this diff will narrow to just the AP-019 component-library changes.

Clicking Save triggers a small notification that pops up in the top-right corner of the screen, stays visible for about 3 seconds, then disappears automatically — nothing changes in the form layout itself.

[Krisha190235]

Really clean component library — FormField, Toast, Pagination, EmptyState, ConfirmDialog are well-scoped and documented, and I like that you proved it on a real page (SMTP) rather than in isolation. SMTP logic still matches the backend (requires host/port/user/pass/from, sends full settings) 👍

One thing before merge: this overlaps with #464 — both rewrite SMTPSettings.jsx from the same base, so they'll conflict. Since #498 is basically #464 rebuilt on the new shared components, I'd suggest we land #498 and close #464 (or rebase #464 out). Let's not merge both.

Small non-blockers: the toasts could use role="status" / aria-live="polite" so screen readers announce them; and ConfirmDialog/EmptyState/Pagination aren't used yet (fine as library scaffolding). Could you also drop a screenshot or two of the toast + form states as evidence?

Otherwise LGTM once we've sorted the #464 overlap