organic-os v0.5.5 - the queue rebuild no longer dies quietly

A follow-on to 0.5.4, found by running the fix against a real brain instead of trusting it.

content-engine writes a draft sidecar next to the brief it belongs to. The queue rebuild globbed every markdown file in the folder, read the sidecar as an item, and raised on its missing status field. On its own that was a crash. Combined with the best-effort wrapper added in 0.5.4 - which exists so a bookkeeping refresh can never block a real state transition - it became worse than a crash: any brain containing a drafted brief would swallow the error and stop refreshing its queue permanently, with no sign anything was wrong.

Drafts are now skipped, since a draft is not an item. An item that parses but lacks the frontmatter every item is born with is reported as malformed rather than raising, because this code runs inside a swallow-everything guard and an exception there is invisible by construction.

The lesson is the release note: a best-effort wrapper turns a loud failure into a silent one. Anything running inside one has to be defensive on its own terms.

441 tests, 9 audit checks, 8 gate probes, CI green.