fix(canvas/a11y): add type="button" to BatchActionBar, EmptyState, SidePanel, CreateWorkspaceDialog

WCAG 4.1.2 / bug #1669 follow-up — buttons without explicit type="button"
default to type="submit", risking accidental form submission.

Added type="button" to all action buttons in:
- BatchActionBar.tsx: Restart All, Pause All, Delete All, Clear Selection (4)
- EmptyState.tsx: template deploy buttons + Create blank (all)
- SidePanel.tsx: close panel, tab switches, Restart Now (3)
- CreateWorkspaceDialog.tsx: open trigger, Cancel, Create (3)

Total this commit: +12 insertions / 2 deletions across 4 files.
Prior commit (c5590c0c): ConfirmDialog + AuditTrailPanel + DeleteCascadeConfirmDialog (+7).
Combined batch: 19 buttons fixed across 7 components.

86 vitest tests pass across all touched test files.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

canvas/src/components/BatchActionBar.tsx

@@ -91,6 +91,7 @@ export function BatchActionBar() {
 
       {/* Action buttons */}
       <button
+        type="button"
         disabled={busy}
         onClick={() => setPending("restart")}
         className="flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-[12px] font-medium text-sky-300 bg-sky-900/30 hover:bg-sky-800/50 border border-sky-700/30 hover:border-sky-600/50 transition-colors disabled:opacity-50 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-sky-500/70"
@@ -100,6 +101,7 @@ export function BatchActionBar() {
       </button>
 
       <button
+        type="button"
         disabled={busy}
         onClick={() => setPending("pause")}
         className="flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-[12px] font-medium text-amber-300 bg-amber-900/30 hover:bg-amber-800/50 border border-amber-700/30 hover:border-amber-600/50 transition-colors disabled:opacity-50 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-amber-500/70"
@@ -109,6 +111,7 @@ export function BatchActionBar() {
       </button>
 
       <button
+        type="button"
         disabled={busy}
         onClick={() => setPending("delete")}
         className="flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-[12px] font-medium text-red-300 bg-red-900/30 hover:bg-red-800/50 border border-red-700/30 hover:border-red-600/50 transition-colors disabled:opacity-50 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-red-500/70"
@@ -121,6 +124,7 @@ export function BatchActionBar() {
 
       {/* Deselect */}
       <button
+        type="button"
         disabled={busy}
         onClick={clearSelection}
         aria-label="Clear selection"

canvas/src/components/CreateWorkspaceDialog.tsx

@@ -211,7 +211,7 @@ export function CreateWorkspaceButton() {
   return (
     <Dialog.Root open={open} onOpenChange={setOpen}>
       <Dialog.Trigger asChild>
-        <button className="fixed bottom-6 right-6 z-40 px-5 py-2.5 bg-blue-600 hover:bg-blue-500 active:bg-blue-700 text-sm font-medium rounded-xl text-white shadow-lg shadow-blue-600/20 hover:shadow-xl hover:shadow-blue-500/30 transition-all duration-200 flex items-center gap-2">
+        <button type="button" className="fixed bottom-6 right-6 z-40 px-5 py-2.5 bg-blue-600 hover:bg-blue-500 active:bg-blue-700 text-sm font-medium rounded-xl text-white shadow-lg shadow-blue-600/20 hover:shadow-xl hover:shadow-blue-500/30 transition-all duration-200 flex items-center gap-2">
           <svg
             width="14"
             height="14"
@@ -432,11 +432,12 @@ export function CreateWorkspaceButton() {
 
           <div className="flex justify-end gap-2.5 mt-6">
             <Dialog.Close asChild>
-              <button className="px-4 py-2 bg-zinc-800 hover:bg-zinc-700 text-sm rounded-lg text-zinc-300 transition-colors">
+              <button type="button" className="px-4 py-2 bg-zinc-800 hover:bg-zinc-700 text-sm rounded-lg text-zinc-300 transition-colors">
                 Cancel
               </button>
             </Dialog.Close>
             <button
+              type="button"
               onClick={handleCreate}
               disabled={creating}
               className="px-5 py-2 bg-blue-600 hover:bg-blue-500 active:bg-blue-700 text-sm rounded-lg text-white disabled:opacity-50 transition-colors"

canvas/src/components/EmptyState.tsx

@@ -110,6 +110,7 @@ export function EmptyState() {
               const tierColor = TIER_CONFIG[t.tier]?.border || TIER_CONFIG[1].border;
               return (
                 <button
+                  type="button"
                   key={t.id}
                   onClick={() => deploy(t)}
                   disabled={!!deploying}
@@ -140,6 +141,7 @@ export function EmptyState() {
 
         {/* Create blank */}
         <button
+          type="button"
           onClick={createBlank}
           disabled={!!deploying}
           className="w-full rounded-xl border border-dashed border-zinc-700/60 bg-zinc-900/30 px-4 py-3 text-sm text-zinc-400 hover:text-zinc-200 hover:border-zinc-600 hover:bg-zinc-900/50 transition-all disabled:opacity-50 disabled:cursor-not-allowed disabled:hover:text-zinc-400 disabled:hover:border-zinc-700/60 focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500/70"

canvas/src/components/SidePanel.tsx

@@ -178,6 +178,7 @@ export function SidePanel() {
           </div>
         </div>
         <button
+          type="button"
           onClick={() => selectNode(null)}
           aria-label="Close workspace panel"
           className="w-7 h-7 flex items-center justify-center rounded-lg text-zinc-500 hover:text-zinc-200 hover:bg-zinc-800/60 transition-colors"
@@ -221,6 +222,7 @@ export function SidePanel() {
       >
         {TABS.map((tab) => (
           <button
+            type="button"
             key={tab.id}
             id={`tab-${tab.id}`}
             role="tab"
@@ -246,6 +248,7 @@ export function SidePanel() {
         <div className="px-4 py-2 bg-sky-950/20 border-b border-sky-800/20 flex items-center justify-between">
           <span className="text-[10px] text-sky-300/90">Config changed — restart to apply</span>
           <button
+            type="button"
             onClick={() => {
               useCanvasStore.getState().restartWorkspace(selectedNodeId).catch(() => showToast("Restart failed", "error"));
             }}