fix(plugins): collect quarantined batches instead of leaving them on disk forever

Review finding. _sweep_debris globbed only *.partial. The *.corrupt files this
PR writes when a batch cannot be decoded are matched by no glob in the module, so
they accumulated for the life of the install.

Collected on the expiry window rather than the stale window, deliberately: a
quarantined batch is the only remaining evidence of events that could not be
delivered, so someone chasing a report of missing telemetry has to be able to
find a recent one. Debris keeps the short window; it carries nothing.

One test, asserting both halves: a recent quarantine survives and an expired one
does not.

Claude-Session: https://claude.ai/code/session_01C7tEmH86HAr7GoAAKCEHZb

integrations/codex-plugin/core/telemetry.py

@@ -462,10 +462,16 @@ def _claim_spool() -> Path | None:
 
 
 def _sweep_debris(directory: Path) -> None:
-    """Remove temp files orphaned by a crash between write and rename.
+    """Remove files nothing else will ever pick up again.
 
-    Neither glob in this module matches *.partial, so nothing else would ever
-    clean them up.
+    *.partial is a temp file orphaned by a crash between write and rename.
+    *.corrupt is a batch quarantined for undecodable content. No glob in this
+    module matches either, so without this they accumulate on disk for the life
+    of the install.
+
+    Quarantined batches are kept far longer than debris: they are the only
+    evidence left of events that could not be delivered, and someone diagnosing
+    a report of missing telemetry has to be able to find one.
     """
     now = time.time()
     for debris in directory.glob("telemetry-*.partial"):
@@ -474,6 +480,12 @@ def _sweep_debris(directory: Path) -> None:
                 debris.unlink()
         except OSError:
             continue
+    for quarantined in directory.glob("telemetry-*.corrupt"):
+        try:
+            if now - quarantined.stat().st_mtime > CLAIM_EXPIRY_SECONDS:
+                quarantined.unlink()
+        except OSError:
+            continue
 
 
 def _claim_parked(directory: Path) -> Path | None: