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

.github/workflows/v2-ci.yml

@@ -114,9 +114,6 @@ jobs:
   # OpcUaServer.IntegrationTests) was removed as fully redundant — the unit-tests leg
   # above already runs BOTH projects under the identical filter, fixtureless, and gates
   # them at the MIN_EXECUTED floor. Its only unique output was a report-only skip tally the unit
-  # leg's trx already contains. FOLLOW-UP (S-2 option #2): if a fixture-backed integration
-  # leg is wanted, add it as a NEW job that starts the one public-image fixture as a
-  # `services:` block (mcr.microsoft.com/iotedge/opc-plc; the modbus/S7/AB/FOCAS sims are
-  # locally-built `otopcua-*` images not pullable here), sets OPCUA_SIM_ENDPOINT, and gates
-  # at a MIN_EXECUTED floor so a fixture outage turns the job red — covering something the unit
-  # leg cannot, rather than re-running the same fixtureless tests.
+  # leg's trx already contains. The fixture-backed leg now lives in its own
+  # workflow, v2-integration.yml (#757), and the guarded fleet E2E in v2-e2e.yml — kept out of this file
+  # so this job's runtime and flakiness are unchanged.