node-postgres returns NUMERIC columns as strings by default. Add a
mapSeq() helper that parses frame_rate to a JS float before any response
is sent. Affected routes: GET /, POST /, PUT /:id, GET /:id.
sequences.js had the same `if (rem >= DROP)` bug as timecode.js — any
frame ≥ 4 in the first non-drop minute of each 10-minute group would
produce a timecode offset by one minute. EDL files exported from the
editor would have wrong in/out points for nearly every event.
Applies the FRAMES_FIRST_MIN (3600) boundary check fix, matching the
correction already made to services/web-ui/public/js/timecode.js.
