Fix: Harden the transfer flow for unexpected data

[photovoltex]

Fixes the transfer flow handling when the context_uri is empty and the context has no tracks. I'm still not sure how this can happen, but some users seem to have encountered it so this should improve the handling for these specific cases.

Additionally the grayed out play/pause button when transferring was fixed and should now stay enabled during transfering.

Fixes #1566

[Copilot]

Pull Request Overview

This PR improves the robustness of the transfer flow by handling edge cases where context_uri is empty and the context has no tracks. It addresses user-reported issues where transfers would fail under these conditions.

• Added fallback handling for empty track contexts during transfers
• Enhanced error handling for context retrieval failures
• Updated the initial transfer handler to accept and use the context URI

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
connect/src/state/transfer.rs	Updated initial transfer handler to accept context URI parameter and set player context fields
connect/src/spirc.rs	Added fallback logic for empty track contexts and improved error handling for context retrieval
CHANGELOG.md	Documented the bug fix and reorganized existing entries

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