feat: dark mode fix, call wallpaper, setTheme error handling, Sentry filter

- CallEmbed: inject :root { color-scheme } into iframe so EC respects Cinny
  theme regardless of OS preference (fixes white background in dark mode)
- CallEmbed: store themeKind, update color-scheme CSS on live setTheme() calls
- CallEmbed: catch transport.send() rejection in setTheme() to prevent
  unhandled promise rejection when widget not ready yet (fixes REACT-8)
- CallEmbed: html + body both set to background:none so wallpaper shows through
- CallEmbedProvider: apply chatBackground wallpaper style to call embed
  container in full-view mode (not PiP) -- wallpapers carry over to calls
- useCallEmbed: pass themeKind through to CallEmbed constructor
- index.tsx: ignoreErrors: [Request timed out] to suppress matrixRTC
  heartbeat timeouts (REACT-9) from Sentry noise
- README: document 0.19.4, positioning fix, dark mode fix, wallpaper,
  millify Rolldown interop fix, Sentry noise filter

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

README.md

@@ -46,7 +46,7 @@ A full custom theme engine layered on top of Cinny's vanilla-extract theming:
 
 ### Voice / Video Call Improvements
 
-- **Element Call 0.19.3**: Upgraded from 0.16.3. Dist copied to `public/element-call/` by vite at build time.
+- **Element Call 0.19.4**: Upgraded from 0.16.3. Dist copied to `public/element-call/` by vite at build time.
 - **Camera default OFF**: Camera no longer persists across sessions via localStorage. Always starts disabled. Optional `cameraOnJoin` setting for explicit opt-in.
 - **Deafen button**: Tooltip corrected to "Deafen" / "Undeafen" (was "Turn Off Sound" / "Turn On Sound")
 - **Screenshare confirmation**: A confirm dialog appears before screenshare is broadcast to call participants
@@ -63,6 +63,9 @@ A full custom theme engine layered on top of Cinny's vanilla-extract theming:
 - **Poll display**: `m.poll.start` events (both stable Matrix 1.7 `m.poll` content key and MSC3381 unstable `org.matrix.msc3381.poll.start`) render as read-only poll cards inside the standard message bubble — question and answer options shown. Registered as top-level event renderers AND inside the `EncryptedContent` callback so encrypted polls also display after decryption. "Open in Element to vote" note displayed. Implemented in `PollContent.tsx`.
 - **Deleted message placeholder**: Redacted `m.room.message`, `m.room.encrypted`, and `m.sticker` events no longer disappear from the timeline. Instead they reach the existing `RedactedContent` component (trash icon + italic "This message has been deleted" with reason if provided), matching Element, FluffyChat, Commet, and Nheko behaviour. One-line change in the `eventRenderer` filter in `RoomTimeline.tsx`.
 - **Picture-in-picture (PiP)**: When navigating away from a call room while in an active call, the call embed shrinks to a 280x158px floating window in the bottom-right corner. The PiP window is **draggable** — drag it anywhere on screen to move it out of the way. Clicking (without dragging) navigates back to the call room. Drag vs click distinguished by a 5px movement threshold; touch drag supported. Imperative style overrides on `callEmbedRef.current` via `useEffect` — a wrapper div cannot be used because `useCallEmbedPlacementSync` writes `top/left/width/height` directly onto that element.
+- **Call embed positioning**: `useCallEmbedPlacementSync` uses `getBoundingClientRect()` (not `offsetTop/Left`) for accurate viewport-relative coordinates on the `position:fixed` container. Position is synced immediately on mount via `useEffect` in addition to the ResizeObserver, so the embed is placed correctly the instant the call view renders. The `[pipMode, callVisible]` effect in `CallEmbedProvider` only clears pip-specific styles when actually exiting pip mode — no longer clobbers the position set by `syncCallEmbedPlacement` on every `callVisible` toggle.
+- **Dark mode in element-call**: After joining, `CallEmbed.applyStyles()` injects `:root { color-scheme: dark|light }` into the iframe document so `@media (prefers-color-scheme)` rules inside element-call resolve to the correct Cinny theme regardless of the OS system preference. `themeKind` is stored on the `CallEmbed` instance and updated on every `setTheme()` call, so live theme switching also re-injects the CSS. Without this, users with OS light mode would see a white background even when Cinny is in dark mode.
+- **Call embed wallpaper**: The user's `chatBackground` pattern (Blueprint, Carbon, Stars…) is applied as the `backgroundImage`/`backgroundColor` of `div[data-call-embed-container]` when the call is in full view (not PiP). The iframe `html, body` is forced to `background: none !important` so the pattern shows through. When `chatBackground` is `none`, behaviour is unchanged.
 
 ### Messaging Enhancements
 
@@ -116,6 +119,8 @@ Emoji reaction buttons styled for terminal mode via `button[data-reaction-key]`
 
 - **Authenticated media**: All avatar/media loads use `mxcUrlToHttp(mx, mxcUrl, useAuthentication, w, h, 'crop')` from `../../utils/matrix` — the Lotus utility that handles MSC3916 authenticated media. (Upstream Cinny uses the SDK method with incorrect argument order for authenticated endpoints.)
 - **Upstream tracking**: `git remote add upstream https://github.com/cinnyapp/cinny.git`. Merge strategy: `git fetch upstream && git merge upstream/main`. Daily check via `cinny-upstream-check.sh` on LXC 106 — notifies Matrix on new upstream commits.
+- **Rolldown CJS interop — millify**: `src/app/plugins/millify.ts` uses a named import (`import { millify as millifyPlugin } from 'millify'`) instead of a default import. Rolldown's `__toESM` helper with `mode=1` sets `a.default = module_object` (not the function itself) when `hasOwnProperty` prevents the copy — calling `millifyPlugin()` would throw `(0, zc.default) is not a function`. Named import bypasses the interop entirely.
+- **Sentry noise filter**: `ignoreErrors: ['Request timed out']` added to `Sentry.init` in `src/index.tsx` to suppress unhandled rejections from the matrixRTC delayed-event heartbeat (matrix-sdk) and the widget PostmessageTransport initial-load race (matrix-widget-api). Neither is actionable from client code.
 
 ---
 
@@ -157,4 +162,6 @@ Built files are served from `/var/www/html/` on LXC 106 (nginx). Config lives at
 | `src/app/components/GifPicker.tsx` | GIF search + send |
 | `src/app/features/call/CallControls.tsx` | PTT badge + keybind logic |
 | `src/app/plugins/call/CallControl.ts` | EC widget bridge (screenshare revert, PTT mic) |
-| `src/app/components/CallEmbedProvider.tsx` | PiP + draggable call embed |
+| `src/app/components/CallEmbedProvider.tsx` | PiP + draggable call embed, call wallpaper carry-over |
+| `src/app/plugins/call/CallEmbed.ts` | EC widget bridge: iframe setup, `color-scheme` dark/light injection, built-in control hiding, theme sync |
+| `src/app/plugins/millify.ts` | Named import fix for Rolldown CJS interop (prevents `zc.default is not a function` crash) |