docs: cut 1.0.38 changelog

[PeterGuy326]

Cuts the 1.0.38 changelog section. Documents the 5 commits merged into main since the 1.0.37 cut (#457):

Added

• feat(agent): accurate agent_code detection + per-channel agentId for stats #467 — client-side agent_code detection + per-channel agent instance id for usage stats

Fixed

• fix: pipeline PollUntil case-insensitive comparison to fix sheet export hang #462 — dws sheet export hang (case-sensitive poll comparison)
• fix(upgrade): honor --dry-run as preview-only instead of silently upgrading #416 — dws upgrade --dry-run silently performing a real upgrade (bug: dws upgrade --dry-run performs the actual upgrade #364)
• feat(doc): strip server-rejected unsafe chars on markdown write path #465 — dws doc create/update failing on server-rejected control / zero-width chars
• feat: support to disable auto open browser #365 — dws auth login --no-browser flag was defined but never wired

Verification

Docs-only change. The code it documents was integration-verified locally on top of current main before merge: go build ./..., go vet, and go test ./internal/compat/... ./internal/app/... ./internal/auth/... all green.

Next steps after merge: tag v1.0.38 → goreleaser.