applog-pull.ts:391 signature collapse — mars 404s all collapse to one dedup key

applog-pull@mars's signature expression COALESCE(NULLIF(errorMessage,''), detail->>'digest', action) has no route, so every mars 404 collapses to the single signature '404'. mig-012's trigger expression (adds action||' '||route) yields 654 distinct signatures over the same 825 rows. Same underlying rows, two producers: one distinguishing, one collapsing. Found during MARS-587 (coder-mars-cc, 2026-07-30). db-mars-cc's prior 'mars does not have venus's collapse defect' answer was correct for the DB/trigger layer and false as a statement about mars overall — the collapsing expression is TypeScript on disk (applog-pull.ts), a different producer than what was asked about. Fix TBD: align applog-pull's signature expression with the trigger's (include route).