01a0919c - Isolate per-PR exceptions in the all-open A38 sweep

[TaprootFreakAI]

EN:
The all-open A38 sweep now isolates any per-PR exception and keeps scanning, so one fork-approval failure cannot leave Ready conflict PRs unprocessed.
The composite action imports main instead of running the module as __main__, so GuardError identity matches sibling imports.

DE:
Der all-open-A38-Sweep isoliert jede per-PR-Exception und macht weiter, damit ein Fork-Approval-Fehler Ready-Konflikt-PRs nicht unbearbeitet lässt.
Die Composite-Action importiert main statt das Modul als __main__ zu starten, damit GuardError dieselbe Klasse ist wie in den Geschwistermodulen.

Details

Production schedule dfx pr guard on DFXswiss/backend aborted mid-scan with an uncaught traceback:

agent_cli.a38_guard.GuardError: fork workflow approval requires the current base to be included in the head

python -m agent_cli.a38_guard executes the file as __main__. Sibling modules import GuardError from agent_cli.a38_guard, a second module object. The all-open except GuardError therefore missed the raised type and killed the rest of the fleet, including Ready pull requests that still had merge conflicts.

This change:

• catches Exception per PR in the all-open loop (log, error JSON, continue, aggregate exit 1)
• treats a dual-imported GuardError as a guard error in the outer main handler
• invokes the composite action via from agent_cli.a38_guard import main
• keeps the _belongs_to_pull refusal to approve a fork run whose head does not contain the current base
• adds tests for a foreign GuardError class, a plain RuntimeError, single-PR handling, and the action stand-in main

Head: da568db9fe8e1d17f12fa2729eda25c032294e98

[TaprootFreakAI]

EN:
Ready after 3 review passes.
The all-open A38 sweep isolates any per-PR exception so one fork-approval failure cannot abort the rest of the fleet.

DE:
Bereit nach 3 Review-Durchläufen.
Der all-open-A38-Sweep isoliert jede per-PR-Exception, damit ein Fork-Approval-Fehler den Rest der Flotte nicht abbricht.

Details

Head a46337b4d15201fb0f7f4782e0a3764840e0b3e7.

Pass 1 (da568db): Grok quality and logic 0 findings; Codex quality 0; Codex logic 2 findings (invalidate skipped on dual-imported GuardError after publish; action stand-in printed at import).

Pass 2 (20704eb): Grok quality 1 finding (except Exception missing # noqa: BLE001); Grok logic 0.

Pass 3 (a46337b): Grok quality, Grok logic, Codex quality, Codex logic all STATUS complete, 0 findings.