fix(doccano-django): gate record-traffic on a real readiness signal

Pipeline 3597 / 909 (post-compose-render fix) failed at:

  Container ... Error dependency postgres failed to start

Misleading. Real cause: doccano_record_traffic fired its very
first POST /v1/projects against a backend whose port was open but
gunicorn was still booting; the 5xx response failed `curl -fsS`,
set -e killed the script silently, the lane saw a zero-second
"traffic done", SIGINTed keploy ~3s later, and the recording
captured nothing. The "dependency postgres failed" line in the
log is downstream noise from the SIGINT compose-down.

Fix: gate doccano_record_traffic on doccano_wait_for_fixed_token
before any curl fires. /v1/me with the fixed Authorization
header is a stronger readiness signal than wait_for_port: it
proves gunicorn is past boot, auth is wired, the named-volume
token is loaded, and the DB is responsive — all four guarantees
the first POST needs.

Lane scripts can keep their own port-level wait (wait_for_port),
but the sample's flow.sh now refuses to fire traffic until the
backend is genuinely serving. Local smoke-test pattern is
unchanged: bootstrap + record-traffic still work standalone.

Signed-off-by: Akash Kumar <meakash7902@gmail.com>

Author: AkashKumar7902

doccano-django/flow.sh

@@ -99,6 +99,21 @@ doccano_record_traffic() {
     local example_resp example_id
     local p
 
+    # Wait for the backend to actually be SERVING (not just
+    # port-open). Lanes typically wait_for_port before invoking
+    # this function, but a TCP-open backend could still be
+    # gunicorn-booting and 5xx every API call. doccano_wait_for_fixed_token
+    # polls /v1/me with the deterministic auth header until it
+    # returns 200, which is the strongest single-call readiness
+    # signal: it proves gunicorn is past boot, the auth backend
+    # is wired, the named-volume token is loaded, and the DB is
+    # responsive. Without this gate, the very first POST below
+    # (curl -fsS, no `|| true`) fails with a 5xx, set -e kills
+    # the script, the lane's compat_run_record_phase sees a
+    # zero-second "traffic done", SIGINTs keploy ~3s after, and
+    # the recording captures nothing.
+    doccano_wait_for_fixed_token 240 >/dev/null
+
     # Worker-cache warmup. doccano runs 4 gunicorn workers; each
     # worker keeps its own per-process Django ContentType cache and
     # populates it lazily on the first polymorphic-resolver query