feat(maestro): install activity hooks for codex too

The hook installer only ever wrote ~/.claude/settings.json, so a codex
session reported no activity and never posted its first prompt — leaving
it on the daemon's generated handle with no haiku name.

Adds a Target enum (claude-code, codex) over the hook file's location and
event set. One script and one marker serve both; codex swaps Notification
for PermissionRequest and has no StopFailure, so it never reports Error.
Both agents spell the prompt event UserPromptSubmit and put the text in
the payload's `prompt`, so autoname needs no change.

Codex will not run a hook it has not been told to trust; `maestro hooks
install` says so, and the approval stays the operator's.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/SIDEBAR.md

@@ -250,6 +250,10 @@ Two rulings specific to a reported `Error` (#114):
   process changes do not clear it — only the agent itself may withdraw what
   the agent itself reported. Re-reporting `Error` extends the TTL rather than
   stacking reports.
+- **Only Claude Code reports `Error`.** Codex has no counterpart to
+  `StopFailure` in its hook event set, so a codex turn that ends on an API
+  error reports `AwaitingInput` and its card carries no error mark. A card
+  without the mark means "nothing reported a failure", not "nothing failed".
 
 If a client receives an `ActivityState` variant it does not know, it must not
 fail rendering: treat it as `Idle` (neutral/dim, line-2 rules apply as usual)