test(board): pin the "field inserted before neste" class; 16 of 16 mutants die

An independent review ran 16 mutants of the PLAN column against the 461
board checks and 5 survived:
- --row taking neste from a stale index (neste=5d|...)
- --inbox-plan taking neste from a stale index (neste=5d)
- the no-STATE.md record one field short (plan=(ingen STATE.md))
- Nd measured behind NOW instead of behind the last commit
- the '?' branch (a plan with no commit) rendered as '-'

Section 34 part 8 adds a fixture for each: a NESTE with a '|' inside,
pinned exactly in --row and --inbox-plan; a repo with no STATE.md; a repo
whose last commit is 30 days old, so the two definitions give different
numbers; a repo with a plan and no commit. Rebuilt from this tree and run
against the full suite: 16 of 16 mutants now fail it.

The same fixtures exposed two defects, fixed here:
- --inbox-plan took neste as ONE field and cut the prose at its first '|'
  (also in 0.34.0); it now takes that field onward.
- a symlinked PLAN.md was aged by the link's own mtime; it now uses
  stat -L, so the plan's age is the target's.

Docs: CHANGELOG no longer says "field 17 onward" (the index is 18) and
now records the no-STATE.md record fix and the --inbox-plan fix; README's
requirement says macOS, since board.sh uses BSD stat and renders nothing
under GNU stat.

board-selftest 461 -> 478 (badge 978). Suites: coord 257, board 478,
route 73, orders 116, guard 54; npm test 12/12, run after git add.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/board.sh

@@ -838,7 +838,9 @@ printf '%s\n' "$REPOS" | while IFS= read -r d; do
   plancol="-"
   for pl_f in "$d"/PLAN.m[d]; do
     [ "${pl_f##*/}" = "PLAN.md" ] && [ -f "$pl_f" ] || continue
-    pl_m="$(stat -f %m "$pl_f" 2>/dev/null)"
+    # -L: the PLAN's age is the target's mtime; a symlink's own mtime is only
+    # when the link was made.
+    pl_m="$(stat -L -f %m "$pl_f" 2>/dev/null)"
     if [ -z "$pl_m" ] || [ -z "$lastct" ]; then
       plancol="?"
     elif [ "$pl_m" -ge "$lastct" ]; then
@@ -1982,7 +1984,11 @@ inbox_plan() {
     FILENAME==RCF {
       name = $3
       rc_bucket[name] = $1; rc_status[name] = $4; rc_cost[name] = $5
+      # neste is the LAST field and may itself contain a pipe: take field 18
+      # ONWARD, never field 18 alone - a single field cuts the prose at its
+      # first pipe. The index moves with the record.
       rc_dir[name] = $10; rc_neste[name] = $18
+      for (i = 19; i <= NF; i++) rc_neste[name] = rc_neste[name] "|" $i
       next
     }
     {