Closes the producer-side contract gap: the unified Arrow exporter emits
pg_stat_ch.block_format=arrow_events_raw on its OTLP envelope, while
the legacy ArrowBatchBuilder path emits arrow_ipc. The central OTel
collector's routingconnector is supposed to fan batches between the
legacy query_logs_arrow target and the new events_raw target based on
that marker. This test pins the producer half of the contract.

New TAP test t/037_arrow_routing.pl exercises both arms:
- arm 1 (unified=off, arrow_passthrough=on): legacy.jsonl grows,
  events_raw.jsonl and default.jsonl don't.
- arm 2 (unified=on): events_raw.jsonl grows with arrow_events_raw
  in the routed payload, legacy.jsonl and default.jsonl don't.

Stock otelcol-contrib image (matches existing t/024 setup, version
0.120.0). Routingconnector keyed on the resource attribute (where
pg_stat_ch.block_format lives via PopulateResource), two file
exporters writing JSONL to a bind-mounted dir the test reads from.
No CH receiver — the events_raw column-set contract isn't validated
here; that's covered by t/036 (producer Arrow IPC -> direct CH
ingest) and by a separate receiver-faithful test in clickgres-platform.

New helpers in t/psch.pm (psch_routing_collector_available,
psch_start_routing_collector, psch_stop_routing_collector) live on a
separate compose profile + container/ports so the new test can
coexist with t/024's collector if both fire in the same suite.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

t/013_clickhouse_tls.pl's reconnect subtest polled for the resumed
export within 30s of restarting the ClickHouse container. The
exporter's reconnect backoff (stats_exporter.cc PschGetRetryDelayMs)
is exponential — base 1s, doubling per consecutive failure, capped at
60s. Failed flush attempts start accumulating as soon as CH goes
down, well before the container finishes restarting, and the
cumulative wait before the Nth retry is the sum of all prior delays:
1, 3, 7, 15, 31, 63, 123s. A restart slow enough to rack up 5-6
failures — plausible under a loaded CI runner — pushes the
bgworker's next attempt past the 30s mark even though ClickHouse
itself came back much sooner.

Observed exactly this on CI twice in a row while rebasing PR #117
onto post-#116 main: identical assertion, identical 'got 0' failure,
while the same commit had passed cleanly on a less-loaded run days
earlier. Not a regression — the backoff constants and this test's
timeout have coexisted; it just needed a slow enough runner to
surface.

Bump to 90s, comfortably past the 6-failure (63s) cumulative-backoff
case plus round-trip margin.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Addresses review feedback (1 Copilot + 4 Cursor comments) on
t/037_arrow_routing.pl, verified live via prove against a real build
(not just code review):

- Track whether this run started the routing collector
  ($started_routing_collector, set before the eval'd start attempt so
  a partial startup still counts). Only tear it down if so — a
  developer's manually-started collector, or one left behind by a
  crashed prior run, is left alone.
- Move teardown into an END block (with 'local $?' to stop system()
  inside END from clobbering the script's exit code) so cleanup runs
  on every exit path: normal completion, plan skip_all, or a die()
  anywhere in the test body. Previously a die (e.g. the open-or-die
  below) skipped cleanup entirely, leaking the container and its fixed
  host ports (14317, 23133) -- ports t/026_arrow_dump.pl and
  t/036_unified_arrow_e2e.pl rely on being unbound.
- Replace the bare 'open ... or die' on arm 2's spot-check with a
  Test::More SKIP block gated on whether the file actually grew, so a
  growth timeout produces a clean failed assertion instead of aborting
  the script mid-run.
- Add per-arm producer-side bookkeeping (psch_wait_for_export +
  psch_get_stats asserting exported/send_failures), matching the
  existing t/024_otel_export.pl idiom, before the JSONL-growth checks.
  On failure this distinguishes 'producer never exported' from
  'producer exported but routing/collector dropped it'.
- Document the fixed-host-port single-instance-per-machine constraint
  in the header rather than parameterizing container/output naming:
  CI runs the TAP suite sequentially (prove without -j, single TAP
  job), and parameterizing names without also parameterizing the
  ports (14317/23133) wouldn't actually fix concurrent local runs
  while risking t/026 and t/036's assumption that those ports are
  unbound.

Live-run verification surfaced a genuine pre-existing race unrelated
to the above: the otelcol fileexporter writes a JSON line and its
trailing newline as separate writes, and arm 1's node can flush
trailing batches right up through stop(). If arm 2 snapshots its
baselines mid-write, those late bytes get mis-attributed. Added
wait_for_quiet() (polls combined JSONL size across all three files
until stable for 1.5s, 15s cap) before arm 2's baselines to close the
window. Confirmed via 3 live prove runs against a real build: one
initial 11/12 run caught the race, then 12/12 with the collector
auto-started (and torn down after), and 12/12 with the collector
pre-started manually (and correctly left running after).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>