P6.2-A: probe dynamic NamedVariableList before RCB mutation

[masarray]

P6.2-A — Dynamic RCB root-cause evidence

Stacked on P6.1 PR #87. Final engine candidate: d4612fb7fd5d499a70df17110f6191c452340e0c. This patch does not change static RCB planning or activation.

Field evidence driving this patch

On the current SIPROTEC field case, association capability advertises Write + DefineNamedVariableList + DeleteNamedVariableList and exposes many free URCB slots, but the first full dynamic DataSet create aborts the MMS association. P6.1 successfully preserves static reporting after reconnect; P6.2 now isolates the exact dynamic service failure.

Change

• before a ready dynamic report plan mutates any RCB, issue one single-member probation using the exact planned DataSet reference;
• sequence is DefineNamedVariableList -> GetNamedVariableListAttributes -> DeleteNamedVariableList;
• only one already-resolved dynamic member is used;
• capture exact invokeID, request HEX, response HEX (or <none>), receive-routing summary, DataSet/member identity, and MMS association state before/after;
• if probation fails, stop before DatSet/TrgOps/Resv/RptEna writes and return exact failure-stage evidence;
• if Define succeeded but verification loses the association before Delete can run, cleanup now fails closed rather than reporting a false rollback success;
• if probation succeeds and cleanup succeeds, continue the existing full dynamic activation unchanged;
• successful probation is not emitted as warning noise unless the subsequent full activation fails.

Safety

Static plans never enter this probe. A failed dynamic probe cannot mutate an RCB. Existing P6.1 static-preservation semantics and P6 dynamic circuit breaker remain unchanged.

Tests

• static/blocked/missing-DataSet plans cannot enter the probe;
• ready dynamic plan with a resolved point does enter the probe;
• deterministic one-member DefineNamedVariableList request carries exact DataSet/member names;
• exact probe-stage failure classification;
• failed Define requires no cleanup;
• successful Define followed by association loss before Delete is reported as cleanup failure and association loss.

CI

ARIEC .NET CI run 32114322970 (#355): success — public-source verification, restore, build, and complete test suite.

No merge is intended until ARSAS is pinned to this exact commit and the same physical relay is retested.