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/add-existing/AddExisting.tsx

@@ -198,7 +198,7 @@ export function AddExistingModal({ parentId, space, requestClose }: AddExistingM
                 }}
               >
                 <Box grow="Yes">
-                  <Text size="H4">Add Existing</Text>
+                  <Text as="h2" size="H4">Add Existing</Text>
                 </Box>
                 <Box shrink="No">
                   <IconButton size="300" radii="300" onClick={requestClose} aria-label="Close">

src/app/features/call/Controls.tsx

@@ -146,7 +146,6 @@ export function ScreenShareButton({ enabled, onToggle }: ScreenShareButtonProps)
           radii="400"
           size="400"
           onClick={() => onToggle()}
-          aria-label={enabled ? 'Stop Video' : 'Start Video'}
           aria-label={enabled ? 'Stop Screenshare' : 'Start Screenshare'}
           outlined
         >

src/app/features/common-settings/general/RoomEncryption.tsx

@@ -121,7 +121,7 @@ export function RoomEncryption({ permissions }: RoomEncryptionProps) {
                     size="500"
                   >
                     <Box grow="Yes">
-                      <Text size="H4">Enable Encryption</Text>
+                      <Text as="h2" size="H4">Enable Encryption</Text>
                     </Box>
                     <IconButton size="300" onClick={() => setPrompt(false)} radii="300" aria-label="Cancel">
                       <Icon src={Icons.Cross} />

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} />

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>

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 ? (