fix(lotus): capture the microphone mono — stereo interfaces published left-only on Firefox

audioCaptureDefaults set no channelCount, so Firefox captured a 2-channel
audio interface (Scarlett Solo, one XLR mic on input 1) as stereo and,
with browser audio processing off (the ML denoise tier), published it as
is: peers heard the speaker in the left ear only. Chrome downmixes such
captures itself, which is why it only showed on Firefox. Request
channelCount: 1 for mic capture; screenshare audio is captured separately
and is unaffected. Tested. Bumps to 0.25.0-lotus.3.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

embedded/web/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@lotusguild/element-call-embedded",
-  "version": "0.25.0-lotus.2",
+  "version": "0.25.0-lotus.3",
   "files": [
     "README.md",
     "LICENSE-AGPL-3.0",