Cut changelog for 0.2.105

[TheGreatAxios]

Renames ## [Unreleased] to ## [0.2.105] - 2026-08-23 so scripts/release.sh can resolve the release notes section.

Contents of 0.2.105 (six merges already on main after v0.2.104):

PR	Issue	What
#544	CL-6906	Compaction keeps scored work, not retry loops
#545	CL-6926	Sub-agent maxTurns hard cap of 100 removed
#546	CL-6925	run_shell 15s default timeout dropped
#552	CL-6917	inference-error partials carry the error payload; honest exec turnsUsed
#554	CL-6909	Thinking-only replay turns get a stable marker
#555	CL-6911	Context estimates sync incrementally from turn identities

No content changes — heading rename only.

Refs CL-6956.

[linear-code]

CL-6956