### What
Forces `account_id` to be applied consistently in queries and message creation paths.
### Why
Some queries were missing `account_id`, leading to cross-account scans and slow performance in large datasets.
### Changes
* Added `account_id` to the relevant query columns.
* Ensured messages are always created within the correct account scope.
* Updated `created_at` handling where required for consistency.
### Impact
* Prevents cross-account queries.
* Improves query performance.
* Reduces risk of incorrect data access across accounts.
### Notes
No functional behavior change for end users. This is a performance and safety fix.
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