Fix publish workflow failing on the flutter_webrtc pin warning

[hiroshihorie]

Every publish workflow run in this repo's history has failed with exit code 65. The dart-lang reusable publish workflow runs a non-interactive dart pub publish, which treats any validation warning as fatal. Our exact flutter_webrtc pin is intentional (the native WebRTC-SDK pods must match between the two packages) but always produces the 'should allow more than one version' warning, so the workflow can never succeed and every release so far has been published manually.

This replaces the reusable workflow with an inline job that publishes with --force, which downgrades warnings to informational. dart-lang/setup-dart is kept solely for pub.dev auth: with id-token: write it mints a temporary pub.dev token from the GitHub OIDC token and registers it in the shared pub config, which the Flutter-side dart pub publish then picks up. The pub.dev trust configuration is based on repository and tag claims, not the workflow definition, so no changes are needed on the pub.dev side.

[devin-ai-integration]

✅ Devin Review: No Issues Found

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[github-actions]

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patch type="fixed" "Fix audio frame generation"
minor type="added" "Add support for custom audio processing"
major type="changed" "Breaking: Rename Room.connect() to Room.join()"