docs: replace prose placeholders in reproduction steps with executable commands

The audit found ~80 placeholders, and the damaging ones were where the
measuring apparatus itself was prose rather than a command:

  a6  "( curl ... ) & 를 20개 띄우고 wait"  — the 22.2s headline came from this
  a3  "<로그인 반복, sid 를 /tmp/sids 에>"  — the whole RPO measurement
  a3  "<sid 목록>"                          — the control it is compared against
  a5  "<수신 파드IP>"                       — the injection
  a8  writes /tmp/tok, reads /tmp/rt        — self-inconsistent, sent an empty token
  b3  $KC / $RT / $NEW never assigned
  c2  bare kcadm.sh with no kubectl exec
  a1  conntrack tuples written by hand, though the direction flips per restart

Each is now a shell-expandable form: pod IPs from jsonpath, the admin password
from the secret, ids from kcadm --format csv, conntrack tuples derived from
"conntrack -L" with awk rather than transcribed.

Then the rewritten commands were executed against the live cluster, and one
of them failed — the 20-way load generator, written as "kubectl run --rm -i",
lost its output stream twice in a row. That is a trap this series already hit
once, and the rewrite reintroduced it. A-6 now uses a resident probe pod that
collects into a file and is cat-ed once; verified 20/20 lines.

Evidence: docs/evidence/followup/05-command-reproducibility.txt

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

docs/experiment-b2-multi-instance-session.md

@@ -345,7 +345,7 @@ Spring Security 는 DDL 을 두 벌 제공한다.
 #    + spring-boot-starter-jdbc, postgresql 의존성
 
 # 2. 스키마 — PostgreSQL 판본을 써야 한다
-kubectl -n keycloak-lab exec <bff-pod> -- sh -c \
+kubectl -n keycloak-lab exec $(kubectl -n keycloak-lab get pod -l app=bff --field-selector=status.phase=Running -o jsonpath='{.items[0].metadata.name}') -- sh -c \
   'unzip -p /app/app.jar BOOT-INF/lib/spring-security-oauth2-client-*.jar' > /dev/null
 #   실제로는 nested jar 를 풀어서 -postgres.sql 을 꺼낸다
 kubectl -n keycloak-lab exec -i deploy/postgres -- psql -U keycloak -d keycloak < oauth2-pg.sql