[gg582]

Summary

• update bundled libttak from 714aa7c9 to the latest v3.5.2 tag (2d356032)
• replace scrollback capture raw malloc/realloc/free ownership with libttak abstract memory
• bound capture growth before size arithmetic and use scoped map/unmap windows for reads
• release an active capture during session cleanup
• add an overflow regression test that verifies captured bytes flush without attempting a huge copy

Verification

• libttak v3.5.2 clean build
• make -j2
• make unit-test
• make SANITIZE=address,undefined unit-test