feat(DEN-1444): add native schema-v2 task runtime

[ORESoftware]

Closed as superseded by the clean current-main product PR #169, merged as 35d2f08555f7e687e06752c0c36de812ff4da737. The merged seven-file runtime contains the repaired positive-jobs parser, corrected task-state locking, deterministic task semantics, cross-platform read-only certification, and no repair workflow.

[linear-code]

DEN-1444

[ORESoftware]

Superseded by current-main product PR #169.

The replacement preserves this reviewed task-runtime history as the second parent of semantic merge fae7d9de282ae7114bbaa1be60bccf7c9b1602bf, while retaining the complete current-main module/workflow surface. It also replaces the unsupported Clap usize.range(1..) parser, adds the --jobs 0 regression, repairs the shadowed task-state mutex under focused validation, and uses a permanent read-only Ubuntu/macOS/Windows gate.

No implementation history is being discarded or conflict-side-selected. Keeping this stale draft open only schedules redundant checks on an obsolete base, so it should not be merged independently.