Touch-target pass: 44px min on default-size buttons (WCAG 2.5.5)

Applies .mobile-touch-target to 32 default-size <Button> elements (32px
tall, below the mobile minimum) across 9 files for strict WCAG 2.5.5
compliance: Save, Cancel, Delete, Validate SSH, Run job, Build index,
Update connection, Add service, etc. Plus the shared DialogFooter Cancel
+ Confirm buttons (used by every ConfirmDialog).

The class applies min-height/min-width: 44px only below md
(max-width: 767px); no-op at md+, so desktop sizing is unchanged.

Completes the touch-target audit started in Slice 9 (which covered icon
buttons, size=sm buttons, checkboxes, switches). 122 tests pass; lint/
build green. No new tests (@media queries aren't honored by jsdom).

Refs openspec/changes/mobile-responsive-parity/verify-report.md residual
risk #2.

frontend/src/pages/ServicesPage.tsx

@@ -195,7 +195,7 @@ function CreateServiceDialog({
 					{!draft ? (
 						<div className="flex flex-col gap-2">
 							{types.map((t) => (
-								<Button
+								<Button className="mobile-touch-target"
 									key={t.service_type}
 									variant="outline"
 									onClick={() => setDraft(emptyDraft(t.service_type))}
@@ -287,7 +287,7 @@ export function ServicesPage() {
 				title="Services"
 				description="External services the app talks to. Configure URLs and API keys here; they are encrypted at rest."
 				action={
-					<Button variant="outline" onClick={() => setCreateOpen(true)}>
+					<Button variant="outline" onClick={() => setCreateOpen(true)} className="mobile-touch-target">
 						<Plus className="mr-1 h-3 w-3" />
 						Add service
 					</Button>