[Chore/Refactor] Add missing 'type' attribute on 'button' components (#26249)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: asukaminato0721 <30024051+asukaminato0721@users.noreply.github.com>

web/app/components/base/theme-selector.tsx

@@ -54,7 +54,7 @@ export default function ThemeSelector() {
       </PortalToFollowElemTrigger>
       <PortalToFollowElemContent className='z-[1000]'>
         <div className='flex w-[144px] flex-col items-start rounded-xl border-[0.5px] border-components-panel-border bg-components-panel-bg-blur p-1 shadow-lg'>
-          <button
+          <button type="button"
             className='flex w-full items-center gap-1 rounded-lg px-2 py-1.5 text-text-secondary hover:bg-state-base-hover'
             onClick={() => handleThemeChange('light')}
           >
@@ -66,7 +66,7 @@ export default function ThemeSelector() {
               <RiCheckLine className='h-4 w-4 text-text-accent' />
             </div>}
           </button>
-          <button
+          <button type="button"
             className='flex w-full items-center gap-1 rounded-lg px-2 py-1.5 text-text-secondary hover:bg-state-base-hover'
             onClick={() => handleThemeChange('dark')}
           >
@@ -78,7 +78,7 @@ export default function ThemeSelector() {
               <RiCheckLine className='h-4 w-4 text-text-accent' />
             </div>}
           </button>
-          <button
+          <button type="button"
             className='flex w-full items-center gap-1 rounded-lg px-2 py-1.5 text-text-secondary hover:bg-state-base-hover'
             onClick={() => handleThemeChange('system')}
           >