feat(web): read-write configuration from admin UI
Convert all module settings from read-only to editable fields in the
admin settings page:
- Core: host, port, base_url (read-only stays read-only)
- Schemas: directory, default (count stays read-only)
- Database: host, port, name, user, password, sslmode (dropdown),
max_connections
- Storage: endpoint, bucket, use_ssl (checkbox), region
- Auth: local/ldap/oidc sub-sections with enabled checkboxes,
connection fields, and secret fields (password input for redacted)
New field components: SelectField (dropdown), CheckboxField (toggle).
Redacted fields now render as password inputs with placeholder.
Auth uses nested key handling to send sub-section objects.
Backend already persists overrides and flags restart-required changes.
Closes #117
fc4826f576