The upstream merge in PR #7240 introduced channel-based database path
separation, causing non-latest/beta channels (including local dev) to
open a different DB file (e.g. kilo-local.db) instead of kilo.db. This
made all existing sessions invisible.
Remove the channel-based path logic and always use kilo.db. Also remove
the now-unused KILO_DISABLE_CHANNEL_DB flag.
Closes#7472
The test now validates that the database file is named according to the current installation channel (latest/beta get 'opencode.db', others get sanitized names). This ensures users' data is stored in the correct location based on their update channel.