fix(linux): restore meeting prompts for later calls on Linux

[IdrisGit]

Summary

Fixes meeting notifications becoming stuck after the first detected call on Linux.

Users will now receive prompts for later meetings after the previous meeting ends. Closing a notification through Hyprland also releases it correctly instead of blocking future prompts.

Behavior

• Ignores OpenWhispr’s own microphone activity when deciding whether a meeting is still active.
• Allows a later calling application to trigger a new prompt.
• Avoids repeated prompts during the same ongoing call.
• Preserves the five-minute cooldown when the user explicitly clicks Dismiss.
• Preserves the 30-second automatic expiry without applying a cooldown.

fixes #1917