feat(plc): ephemeral soft-PLC provisioning + program load (#183)

Dynamic PLC testing without reaching the customer's device: when a PLC/SPS
target ships control logic but no reachable live URL, instantiate that logic
ourselves on a throwaway OpenPLC container in-cluster, load + start it, probe
the provisioned Modbus endpoint, and tear it down. No customer network access,
sandboxed, and reproducible.

This is the phase-1 foundation of epic #183 (OpenPLC substrate). It covers:

- provision: ephemeral container lifecycle (docker CLI). Resource-capped
  (memory/cpus/pids), hardened (no-new-privileges), labelled, joined to the
  agent's own network with no host port exposure, and swept by a stale reaper
  for anything a crashed run leaks. The `docker` argv is built by pure functions
  so it is unit-tested without a daemon.
- openplc: drives the OpenPLC web UI to load a program — login → upload →
  save → compile (MatIEC) → start_plc (which opens Modbus/TCP 502).
- runtime::provision_and_test: composes them under a hard deadline with
  guaranteed teardown on every path (success / error / timeout), then runs the
  existing ICS probe against the provisioned endpoint. extract_program picks the
  best loadable program (complete ST > largest ST > PLCopen XML).
- orchestrator: for a PlcSps target with control logic and no live URL, run
  provision-and-test after the static PLC scan. Gated by PlcRuntimeConfig
  (PLC_RUNTIME_ENABLED, default off — needs Docker access in the agent).

DAST-against-WebVisu and CODESYS-runtime fidelity are follow-ups.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Cargo.toml

@@ -23,7 +23,7 @@ tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 chrono = { version = "0.4", features = ["serde"] }
 mongodb = { version = "3", features = ["rustls-tls", "compat-3-0-0"] }
-reqwest = { version = "0.12", features = ["json", "rustls-tls", "multipart"], default-features = false }
+reqwest = { version = "0.12", features = ["json", "rustls-tls", "multipart", "cookies"], default-features = false }
 thiserror = "2"
 sha2 = "0.10"
 hex = "0.4"