stop the harness before deleting its transcript, and wait for it to actually stop

Deleting a commander removed its transcript and the `claude` CLI wrote it
straight back. Verified rather than inferred: the file returned with 22 lines,
every one timestamped after the delete, and the deleted commander was sitting in
/chat as "(untitled)" — no longer in `command_hq_sessions`, so nothing filtered
it out. Delete a commander, get an untitled chat back.

Two causes, and the first one hid the second.

The kill never happened. `killClaudeSession` was imported straight from
`claude-manager` into a route that runs in `officer`, while the session map lives
in `officer-claude-code`. It read an empty map in the wrong process and returned
false every time. `claude:kill` and `killClaude` already existed for this; the
route just wasn't using them.

And killing is not being dead. `abort()` returns while the CLI is still
unwinding, and officer does not own that file — the CLI does. So a session now
carries an `exited` promise resolved by the same exit hook that already reaps it,
`claude:kill` replies only once that resolves, and both delete routes await the
reply before touching the filesystem.

Bounded at 5s and never fatal. A child that will not die delays a delete by
seconds instead of hanging it, and a sidecar that is down leaves the caller with
exactly the race it already had.

`markExited` fires before `dropDeadSession`'s identity guard, deliberately: a
waiter has to be released even when a newer session has taken its key, or it
blocks for the full timeout on a process that died on schedule.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/servers/sidecar-registry.ts

@@ -330,6 +330,26 @@ export function killClaude(sessionKey: string, userId: number): void {
   sendFire('claude', { type: 'claude:kill', id: nextId(), sessionKey, userId });
 }
 
+/**
+ * Kill a session and wait for the agent to confirm its child process is gone.
+ *
+ * For callers that then delete the session's FILES. The transcript belongs to the `claude` CLI, not to
+ * officer, so removing it while the CLI is still unwinding deletes a file that is written straight back —
+ * which resurrects a conversation the user deleted, as an untitled ordinary chat that nothing filters out.
+ *
+ * Never fatal: a sidecar that is down or slow must not block a delete. The caller proceeds and accepts the
+ * race it was already running, which is no worse than before this existed.
+ */
+export async function killClaudeAndWait(sessionKey: string, userId: number): Promise<boolean> {
+  try {
+    const sc = await waitForHandler('claude');
+    const res = await sendCommandToSidecar(sc, { type: 'claude:kill', id: nextId(), sessionKey, userId });
+    return res.type === 'claude:killed';
+  } catch {
+    return false;
+  }
+}
+
 // Interrupt the current turn but keep the persistent session warm (the "stop" button).
 export function interruptClaude(sessionKey: string, userId: number): void {
   sendFire('claude', { type: 'claude:interrupt', id: nextId(), sessionKey, userId });