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/room/MembersDrawer.tsx

@@ -366,7 +366,6 @@ export function MembersDrawer({ room, members }: MembersDrawerProps) {
                 radii="Pill"
                 outlined
                 size="300"
-                aria-label="Scroll to Top"
               >
                 <Icon src={Icons.ChevronTop} size="300" />
               </IconButton>

src/app/features/room/RoomInput.tsx

@@ -808,7 +808,6 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
                 variant="SurfaceVariant"
                 size="300"
                 radii="300"
-                aria-label="Share location"
                 title="Share location"
               >
                 {locating ? (