fix(pm-agent): log the CLI's stdout envelope when triage fails; add PM_DECISION_MAX_TURNS

`claude --print --output-format json` reports its own failures (API error, usage limit,
error_max_turns) as the result envelope on stdout and leaves stderr empty, so ask_pm()'s
stderr-only message logged "claude exited 1: " with nothing after it, twice on 2026-10-31.
describe_cli_failure() now logs the envelope's diagnostic fields plus stdout/stderr tails,
redacted (sk-ant-, Bearer/token, URL userinfo). PM_DECISION_MAX_TURNS (default 1, unchanged)
makes the max-turns remedy a ConfigMap change if the envelope turns out to say error_max_turns.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

platform/pm-agent/README.md

@@ -250,6 +250,12 @@ five that matter:
 | `PM_MAX_ACTIVE_WORKERS` | `2` | concurrent workers. RAM is the binding constraint (2Gi limit each) and the subscription seat's rate limits are shared with every other use of that seat |
 | `PM_MAX_NEW_WORKERS_PER_CYCLE` | `1` | drains a backlog one issue at a time instead of in one stampede the first minute the credentials work |
 | `PM_PUSH_ON_RED_GATE` | `false` | a change the gate refused is not pushed; the issue gets the gate log instead |
+| `PM_DECISION_MAX_TURNS` | `1` (unset) | turns the triage call may take (1–5). The PM holds no tools, so a second turn is only ever the CLI re-asking after an answer that failed the decision schema. Raise it if a triage error logs `subtype='error_max_turns'` |
+
+**When a triage fails**, the `[error] issue #N: claude exited …` line carries the CLI's result
+envelope (`subtype`, `is_error`, `api_error_status`, `num_turns`, `result`) and the tails of
+stdout and stderr, redacted. Before 2026-10-31 it logged stderr only, which is empty under
+`--output-format json` — see `decisions/2026-10-31-pm-agent-triage-exit.md`.
 
 Changing a knob requires bumping the `config-generation` annotation in `deployment.yaml` in
 the same commit — the process reads its configuration once, at startup, so without the bump