Title: Allow selecting multiple contexts for a single recording

Description:

Currently, only one context can be assigned when starting a recording. It would be highly valuable to allow selecting multiple contexts at the same time.

Many meetings naturally span across several topics, and restricting recordings to a single context limits organization and later retrieval. By enabling multi context selection, recordings could be categorized more accurately and used more effectively in AI chat and analysis.

Suggested behavior:

1️⃣ Allow selecting multiple contexts in the recording start popup

2️⃣ Enable flexible tagging such as Topic A, Topic B, Topic C

3️⃣ Ensure AI chat can reference all selected contexts seamlessly