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/general/RoomUpgrade.tsx

@@ -103,7 +103,7 @@ function RoomUpgradeDialog({ requestClose }: { requestClose: () => void }) {
               size="500"
             >
               <Box grow="Yes">
-                <Text size="H4">{room.isSpaceRoom() ? 'Space Upgrade' : 'Room Upgrade'}</Text>
+                <Text as="h2" size="H4">{room.isSpaceRoom() ? 'Space Upgrade' : 'Room Upgrade'}</Text>
               </Box>
               <IconButton size="300" onClick={requestClose} radii="300" aria-label="Close">
                 <Icon src={Icons.Cross} />