[browsing] Consume the with-tasks routes as compact NDJSON streams

[frankrousseau]

Problem

• The all-assets and all-shots views download the full with-tasks payload as one JSON document: heavy on the wire and built entirely in server memory, on a route called constantly (up to ~10k shots on series).

Solution

• Request the new Kitsu-only options of [perf] Rework the with-tasks views: flat queries, stream and compact options zou#1143 (stream=true&compact=true): the server streams NDJSON, one entity per line, as positional arrays described by the header field lists (payload halved, server peak 132→58MB on assets and 100→33MB on shots).
• Decode rows in the API client by mapping field names from the header (never by position); stores keep receiving the same list of dicts.
• Fall back to the legacy plain JSON request on any non-NDJSON answer, so an up-to-date Kitsu keeps working against an older Zou.