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/ServicePage.tsx

@@ -212,7 +212,11 @@ export function ServicePage() {
 							<Label htmlFor="service-enabled">Enabled</Label>
 						</div>
 						{configFields}
-						<Button variant="destructive" onClick={() => setDeleteOpen(true)}>
+						<Button
+							className="mobile-touch-target"
+							variant="destructive"
+							onClick={() => setDeleteOpen(true)}
+						>
 							Delete service
 						</Button>
 						{widgetsCard}
@@ -252,10 +256,18 @@ export function ServicePage() {
 						<Label htmlFor="service-enabled">Enabled</Label>
 					</div>
 					<div className="flex justify-between">
-						<Button onClick={save} disabled={saveService.isPending}>
+						<Button
+							className="mobile-touch-target"
+							onClick={save}
+							disabled={saveService.isPending}
+						>
 							Save
 						</Button>
-						<Button variant="destructive" onClick={() => setDeleteOpen(true)}>
+						<Button
+							className="mobile-touch-target"
+							variant="destructive"
+							onClick={() => setDeleteOpen(true)}
+						>
 							Delete
 						</Button>
 					</div>
@@ -392,7 +404,9 @@ function ServiceConnectionFields({
 				</div>
 			)}
 
-			<Button onClick={handleUpdateConnection}>Update connection</Button>
+			<Button className="mobile-touch-target" onClick={handleUpdateConnection}>
+				Update connection
+			</Button>
 		</div>
 	);