Viewer: trails of 25+ hops fail "Read as flow"; trail limits disagree (store 64, flow 24, nodes 60) #1976

The viewer's trail size limits disagree, so ordinary long walks fail:

On main (ba3c21e):

/api/flow with 24 hop= params     → 200
/api/flow with 25 hop= params     → 400 "A trail of 25 hops is longer than this endpoint reads (24)."
/api/nodes with 61 id= params     → 400 "Too many ids: 61. At most 60 per request."

Effect:

• The trail bar's "Read as flow" sends the whole trail, so any walk of 25 or more hops shows an error instead of a flow. That includes trails the store happily saves at up to 64 hops.
• resolveTrailNames sends every unnamed hop in one /api/nodes request, so a cold load of a 61–64 hop trail link never resolves its names.

Suggested fix: make one limit the source of truth. Either cap the trail when a hop is pushed, or raise /api/flow to the store's 64. Have the client split /api/nodes calls into batches of 60.