organic-os v0.5.0 - memory integrity and honest boundaries

Patterns adopted from Garry Tan's gstack (https://github.com/garrytan/gstack), filtered through this project's own philosophy. Studying it exposed three gaps that were real in our code, not hypothetical.

• Durable decisions, consulted before re-deciding. The brain created a decisions/ directory and then never wrote to or read it, so the loop could re-propose work a human had already rejected, forever. Rejecting an item now records a searchable decision with the reason, and the skills that create work search it first. Re-proposing is allowed; doing it silently is not - the proposal must say what changed since the rejection.
• Lessons expire by evidence tier. Skillbook entries always carried a last-confirmed date that nothing ever acted on. Anecdotal lessons now go stale at 90 days, moderate at 180, strong at 365, and the weekly reflection surfaces them for re-validation. Nothing is ever auto-deprecated; a human decides.
• An advisory redaction scan before outbound content. Six sinks pushed brain content outward with no guard. Findings are tiered and excerpts are masked, and the docs are blunt about the limit: this reports, it does not prevent. A high-tier finding means a credential already left.
• /organic-os:diagnose, the honest alternative to telemetry. It assembles exactly the report telemetry would have sent, scans its own output first, reports credentials only as present or absent, and then prints it for you to paste or discard. It never transmits. There is still no telemetry in this project and ADR-0011 records why, along with the trigger that would justify revisiting.
• Causes require the check that was run. A cause may not be asserted without naming the comparison actually performed. If it was not run, the cause is unknown - seasonality is not an explanation unless somebody compared the same weekday in the prior period.
• /organic-os:verify-outcome recomputes a claim independently. It reads only the item, the URL and the date windows, pulls the raw data, computes the delta, and compares to what was claimed afterwards. Divergence is recorded as a finding. The standard evidence.md applies to other people's claims now applies to our own.

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