Add form styles and update button classes for consistency

- Introduced a new CSS file for form styles (forms.css) to enhance form layout and design.
- Removed deprecated button styles from imports.css and updated button classes across templates to use the new utility classes.
- Updated various templates to reflect the new button styles, ensuring a consistent look and feel throughout the application.
- Refactored form-related styles in main.css and removed redundant styles from projects.css and scenarios.css.
- Ensured responsive design adjustments for form actions in smaller viewports.

static/css/forms.css

@@ -0,0 +1,102 @@
+.form {
+	display: flex;
+	flex-direction: column;
+	gap: 1.25rem;
+}
+
+.form-grid {
+	display: grid;
+	grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
+	gap: 1.25rem;
+}
+
+.form-group {
+	display: flex;
+	flex-direction: column;
+	gap: 0.5rem;
+}
+
+.form-group label {
+	font-weight: 600;
+	color: var(--text);
+}
+
+.form-group input,
+.form-group select,
+.form-group textarea {
+	padding: 0.75rem 0.85rem;
+	border-radius: var(--radius-sm);
+	border: 1px solid var(--card-border);
+	background: rgba(8, 12, 19, 0.78);
+	color: var(--text);
+	transition: border-color 0.15s ease, background 0.2s ease,
+		box-shadow 0.2s ease;
+}
+
+.form-group textarea {
+	resize: vertical;
+	min-height: 120px;
+}
+
+.form-group input:focus,
+.form-group select:focus,
+.form-group textarea:focus {
+	outline: 2px solid var(--brand-2);
+	outline-offset: 1px;
+}
+
+.form-group input:disabled,
+.form-group select:disabled,
+.form-group textarea:disabled {
+	cursor: not-allowed;
+	opacity: 0.6;
+}
+
+.form-group--error input,
+.form-group--error select,
+.form-group--error textarea {
+	border-color: rgba(209, 75, 75, 0.6);
+	box-shadow: 0 0 0 1px rgba(209, 75, 75, 0.3);
+}
+
+.field-help {
+	margin: 0;
+	font-size: 0.85rem;
+	color: var(--color-text-subtle);
+}
+
+.field-error {
+	margin: 0;
+	font-size: 0.85rem;
+	color: var(--danger);
+}
+
+.form-actions {
+	display: flex;
+	flex-wrap: wrap;
+	gap: 0.75rem;
+	justify-content: flex-end;
+}
+
+.form-fieldset {
+	border: 1px solid var(--color-border);
+	border-radius: var(--radius);
+	background: rgba(21, 27, 35, 0.85);
+	box-shadow: var(--shadow);
+	padding: 1.5rem;
+	display: flex;
+	flex-direction: column;
+	gap: 1.25rem;
+}
+
+.form-fieldset legend {
+	font-weight: 700;
+	padding: 0 0.5rem;
+	color: var(--text);
+}
+
+@media (max-width: 640px) {
+	.form-actions {
+		justify-content: stretch;
+	}
+}