docs(changelog): receipt the two #76 runtime-api features

The version-drift audit requires every issue-linked `feat` commit in
v0.9.13..HEAD to leave a changelog receipt; `80394f027cf6` (a replay is
distinguishable from a new admission) and `164a25ca3c27` (SSE streams resume
from `Last-Event-ID`) had none, so
`scripts/release/check-feature-release-notes.sh v0.9.13 HEAD` exited 1 with two
errors. Both halves of #76 are client-visible on the runtime API, so they get
`### Added` bullets rather than an archive note.

`crates/tui/CHANGELOG.md` regenerated with `scripts/sync-changelog.sh` (the
in-binary slice, never hand-edited).

Verification:
- `check-feature-release-notes.sh v0.9.13 HEAD` -> exit 0,
  "Feature release-note receipts OK: 55 linked issue reference(s) checked".
- `./scripts/release/check-versions.sh` -> exit 0, "Version state OK:
  workspace=0.10.0, npm=0.10.0, npm-binary=0.10.0, lockfile in sync."
- `check-versions.sh --require-dated-release` -> still exit 1, now with only
  the two release-moment errors (dated heading, compare link at v0.10.0).

CHANGELOG.md

@@ -41,6 +41,18 @@ tag, packages, checksums and release assets exist.
 
 ### Added
 
+- The runtime API tells a replayed submission apart from a new admission:
+  `POST /v1/threads/{id}/turns` answers `200` with `idempotent_replay: true`
+  when the operation key was already used, and `201` for a fresh admission, so a
+  client that retries after a dropped response can no longer create a second
+  turn. The flag is absent on a fresh admission, so responses existing clients
+  already parse are unchanged (#76).
+- Event streams resume where they left off: journal frames carry their durable
+  `seq` as the SSE event `id:`, `Last-Event-ID` is honoured as the cursor when
+  no explicit `since_seq` is asked for, and `RuntimeCapabilities` advertises
+  `event_stream_resume` so a client can gate its reconnect controls on the
+  capability instead of discovering it from a missing id (#76).
+
 - TTFT and average output rate stay visible in the compact working footer when
   space allows. `/statusline` now controls them separately; existing
   `session_metrics` settings still work.

crates/tui/CHANGELOG.md

@@ -41,6 +41,18 @@ tag, packages, checksums and release assets exist.
 
 ### Added
 
+- The runtime API tells a replayed submission apart from a new admission:
+  `POST /v1/threads/{id}/turns` answers `200` with `idempotent_replay: true`
+  when the operation key was already used, and `201` for a fresh admission, so a
+  client that retries after a dropped response can no longer create a second
+  turn. The flag is absent on a fresh admission, so responses existing clients
+  already parse are unchanged (#76).
+- Event streams resume where they left off: journal frames carry their durable
+  `seq` as the SSE event `id:`, `Last-Event-ID` is honoured as the cursor when
+  no explicit `since_seq` is asked for, and `RuntimeCapabilities` advertises
+  `event_stream_resume` so a client can gate its reconnect controls on the
+  capability instead of discovering it from a missing id (#76).
+
 - TTFT and average output rate stay visible in the compact working footer when
   space allows. `/statusline` now controls them separately; existing
   `session_metrics` settings still work.