Go on past cache entries the reconciliation pass cannot read (closes #343)

The walk of each storage directory returned the error of an entry it
could not read. The pass then stopped before its later checks, and the
same entry stopped every later pass. Now reconcileFiles skips a
directory it cannot list and a file whose info it cannot read. It logs
a warning naming the path and the error, and the walk goes on. It reads
each file's info itself and hands it to reconcileVariantFile and
reconcileSourceFile. A cancelled context still stops the walk with its
error. README.md says so under Storage.

Model: opus-5-5

TODO.md

@@ -30,6 +30,14 @@ P2: security: per-origin rate limiting
 
 # Completed Steps
 
+- 2026-10-27 the reconciliation pass skips a directory it cannot list and a file
+  whose info it cannot read, and goes on (closes #343). It returned the error,
+  so one such entry stopped every pass before its later checks.
+    - Each skipped entry gets the warning "skipped unreadable entry in cache
+      directory", with its path and the error.
+    - `reconcileFiles` reads each file's info and hands it to
+      `reconcileVariantFile` and `reconcileSourceFile`.
+    - A cancelled context still stops the walk with its error.
 - 2026-10-26 the reconciliation pass drops a variant's accounting row only when
   its file is missing (closes #340). Any other error reading the file's size
   keeps the row. It dropped the row on any error and logged the file as missing.