Exercise the full test/sql/* sqllogictest suite over all three VGI
transports (subprocess/stdio, HTTP, AF_UNIX), not just subprocess.

- ci/run-integration.sh: parameterize by $TRANSPORT. For http, boot the
  worker with `--http --port 0 --port-file <f>`, poll the port-file, set
  LOCATION=http://127.0.0.1:<port>, and inject `INSTALL httpfs FROM core;
  LOAD httpfs;` after each `LOAD vgi;` (the vgi HTTP transport rides on
  httpfs). For unix, boot with `--unix <sock>` and poll the socket.
  Trap-kill the out-of-band worker; cleanup preserves the real exit code.
  Add a silent-skip guard so a broken http leg cannot fake a pass.
- pyproject.toml + quant_worker.py PEP 723 header: add the `http` extra
  (vgi-python[http] -> waitress). Relock.
- .github/workflows/ci.yml: integration job becomes an os x transport
  matrix; install with `uv sync --frozen --extra http`; export WORKER_CMD.

All three legs GREEN locally (haybarn-unittest): subprocess/unix 38
assertions, http 44 (httpfs inject). Table functions here are discovery TableFunctionGenerator (day_count_conventions) — emit+finish in one tick,
so they terminate correctly over the stateless HTTP transport with no
per-scan cursor state needed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>