fix(a11y): semantic headings, htmlFor/id associations, remove duplicate aria-labels

H-tag: add as=h1/h2 to dialog/UIA/auth headings (21 components)
Label: add htmlFor/id to PasswordRegisterForm (5 pairs) and PasswordResetForm (3 pairs)
Dupe: remove duplicate aria-label from Controls.tsx screenshare button, MembersDrawer, Members, RoomInput

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

src/app/features/common-settings/members/Members.tsx

@@ -283,7 +283,6 @@ export function Members({ requestClose }: MembersProps) {
                   radii="Pill"
                   outlined
                   size="300"
-                  aria-label="Scroll to Top"
                 >
                   <Icon src={Icons.ChevronTop} size="300" />
                 </IconButton>