fn_notify_applog_err: page_not_found signature collapses across all routes

fn_notify_applog_err signature fallback collapses all navigation/page_not_found (and any errorMessage-less, digest-less) rows into one bucket via COALESCE(errorMessage, detail->>digest, action) -- action alone is not route-specific, causing false-recurrence reads on distinct incidents (discovered triaging 488a04a7/comisiones 404s). Fleet-wide bug confirmed identical in venus+mars migrations too (relayed via nw-venus-cc), each project's db agent fixes its own copy. Fix: key signature off route/path for navigation-category rows (e.g. include a path/URL field in the notify payload, or fall back to a route-bearing detail key before action) so distinct routes don't collapse into one signature.