Harden WNN DSM enforcement

[dfeen87]

Motivation

• Ensure the Deterministic Safety Monitor (DSM) fully enforces WNN-derived safety constraints and fails closed on invalid telemetry.
• Make WNN-triggered rollbacks auditable and robust by durably logging events to the Immutable Telemetry Ledger (ITL) and hardening rollback execution checks.

Description

• Strengthened DSM WNN handling by extending WnnTelemetry with defaults and a timestamp_ms, adding an upper oscillatory-prefactor guard (WNN_MAX_OSCILLATORY_PREFACTOR), and rejecting non-finite or negative telemetry values.
• Made threshold checks inclusive and conservative by treating boundary values as breaches and by recording last_estimated_Rmax_, and made DSM fail closed when curvature estimates are non-finite.
• Wire WNN enforcement to durable logging: implemented an ITLManager lifecycle (payload sizing, entry hashing, flash-backed commit, Merkle batching via process_merkle_batch, flush_pending) and changed log_wnn_rollback_event to return success/failure of ledger commits.
• Hardened rollback execution: execute_rollback_plan now rejects non-finite thrust/gimbal values and negative thrust, and trigger_wnn_immediate_rollback validates rollback_count bounds and rollback_store before indexing and emits metrics when rollbacks are rejected or executed.
• Added/updated SIL tests and CMake registration: new tests/sil/test_dsm_wnn.cpp covering nominal WNN behavior, boundary-triggered rollback, invalid telemetry fail-closed behavior, and reversed-dilation shutdown; expanded tests/sil/test_rollback_execution.cpp to cover non-finite thrust and out-of-range rollback count; updated tests/sil/CMakeLists.txt to add the new test target.

Testing

• Built the SIL test tree with cmake -S tests/sil -B build/sil and cmake --build build/sil -j2 which produced the test executables.
• Ran the SIL test suite with ctest --test-dir build/sil --output-on-failure and observed all tests pass.
• Test summary: the SIL test set (including the new DSM WNN tests and updated rollback tests) passed with 0 failures.

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Codex Task