perf: improve mark as read performance

[naveensingh]

Type of change(s)

• Bug fix
• Feature / enhancement
• Infrastructure / tooling (CI, build, deps, tests)
• Documentation

What changed and why

• Applied proper selection when marking messages as read. This was not a big issue before because users rarely marked long threads as read/unread, but the fix in feat: add unread badge count for conversations #560 made Mark as read unconditional on resume, leading to SQLite pool exhaustion.
• Mark as read should work better now due to this change.

Tests performed

• Tested scrolling and sending messages in a thread containing 10,000 fake SMS and MMS messages inserted into the telephony database.

Closes the following issue(s)

• Closes Crashes and App not responding errors in version 1.5.0 #574

Checklist

• I read the contribution guidelines.
• I manually tested my changes on device/emulator (if applicable).
• I updated the "Unreleased" section in CHANGELOG.md (if applicable).
• I have self-reviewed my pull request (no typos, formatting errors, etc.).
• All checks are passing.