fix(issue-26): review round 1 - no file key assigns bash's own variables; SKS_QUIESCENT_TRIES; long decimals

R1 (P1): a quoted export still ran code when the key was a bash special
variable (RANDOM=a[$(cmd)] is evaluated arithmetically on assignment).
envfile.RESERVED (bash's own variables, plus BASH_/COMP_/READLINE_
prefixes) is skipped with a line-numbered warning by both loaders; a test
keeps it covering every variable a clean bash defines. The wrapper also
hands SCRIPT_DIR/REPO_ROOT/TARGET_ENV to the parser as environment, so the
file cannot replace the variables it has already set.

R2 (P2): SKS_QUIESCENT_TRIES reached `for ((i < tries))` through a function
argument; it is normalised at the call site (minimum 0). B5 now requires
every integer-looking env default in the shell code to be normalised or
listed in NOT_ARITHMETIC with where it goes, and exercises _pane_quiescent.

R3 (P2): _positive_int strips leading zeros and rejects more than nine
significant digits before int(), like mam_int; 5000-digit inputs no longer
raise in the runner.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.agents/skills/lib.sh

@@ -2782,7 +2782,7 @@ send_keys_safe() {
   fi
 
   local _q_rc=0
-  _pane_quiescent "$sess" "${SKS_QUIESCENT_TRIES:-20}" "${SKS_QUIESCENT_INTERVAL:-0.5}" || _q_rc=$?
+  _pane_quiescent "$sess" "$(mam_int_knob SKS_QUIESCENT_TRIES 20 0)" "${SKS_QUIESCENT_INTERVAL:-0.5}" || _q_rc=$?
   if [ "$_q_rc" = "1" ]; then
     echo "send_keys_safe: pane never quiesced ($sess)" >&2
     return 1