Fixes both false claims the spec flagged: M1.5 was never 'verified in M1' and M1
did not 'run a read-only feasibility spike' (it deferred it). The spike has now
run separately and passed, so both are updated to point at the findings spec
(smart_search.embedding, 1152-dim, cosine, clean assetId->asset.id join) and the
spike is listed under Related specs.