ci: fixture-backed integration workflow and guarded fleet E2E workflow (lmxopcua#757)

v2-integration.yml runs the Sql, Historian.SqlServer, Historian.QuestDb and OpcUaClient
integration projects against throwaway SQL Server/PostgreSQL/QuestDB/opc-plc containers
started by scripts/ci/integration-fixtures.sh, with a MIN_EXECUTED=440 floor. v2-e2e.yml is
manual/weekly, probes the shared fleet and skips cleanly when unreachable. v2-ci.yml is
functionally unchanged. Unverified on a hosted runner until first run.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

scripts/ci/README.md

@@ -56,3 +56,26 @@ Restore, Release build, README drift check, the serialized whole-solution test
 step, the 12,000-test floor and TRX upload all passed. The floor counted
 14,630 executed tests across 62 TRX files. This baseline predates the individual
 skip-reporting correction; its printed zero skip diagnostic is not skip evidence.
+
+## Fixture-backed integration and guarded E2E workflows (#757)
+
+**Both are UNVERIFIED on a hosted Gitea runner until their first run**; they were validated locally only
+(YAML parse, the exact `dotnet test` commands and fixture script against local throwaway containers).
+Neither touches `v2-ci.yml`; each has its own concurrency group (`lmxopcua-v2-integration`,
+`lmxopcua-v2-e2e`, `cancel-in-progress: false`) so a pending run of one cannot supersede a pending
+`lmxopcua-v2-ci` run.
+
+- **`v2-integration.yml`** (push to `master`, path-filtered PRs, manual; `timeout-minutes: 60`).
+  `integration-fixtures.sh up` starts throwaway SQL Server 2022, PostgreSQL 17 (seeded from `seed-pg.sql`),
+  QuestDB and opc-plc (`otopcua-ci-*`, non-default host ports), exports the env vars the fixtures read, and
+  `down` removes them. It uses plain `docker run`, not `services:` (act_runner support is undocumented and
+  Postgres needs a seed step); the only runner requirement is a docker daemon. Runs the Sql, Historian.SqlServer,
+  Historian.QuestDb, OpcUaClient and OpcUaClient.Browser `*.IntegrationTests` with `MIN_EXECUTED=440`.
+  Local run: 468 executed / 8 skipped (Oracle x2, the blackhole `docker pause` gate, one QuestDB stress test,
+  4 others), about 4.5 min of test time, QuestDB the longest (~3.3 min). Not covered (no pullable image or
+  needs credentials): Modbus/S7/AB/FOCAS/TwinCAT sims, Mqtt, MTConnect, Oracle, Host real-infra mode.
+- **`v2-e2e.yml`** (manual + weekly cron only; `timeout-minutes: 90`). `probe-e2e-fixtures.sh` TCP-probes
+  10.100.0.35 ports 5020/1102/50000; if any is closed every later step is skipped and the run is green with a
+  notice. Otherwise runs the Modbus, S7, OpcUaClient and OpcUaClient.Browser integration projects against the
+  shared fleet with `MIN_EXECUTED=35` (local: 42 executed / 38 skipped; Modbus skips the profiles that are not
+  up). No test carries `Category=E2E` today, so the zero-match guard is this executed floor.