Generate calc_on_order_fills state checkpoints

[luisleo526]

What changed

• plumb calc_on_order_fills from Pine strategy declarations and runtime overrides
• generate snapshot, rollback, and commit hooks for persistent script state
• move synthesized history-call and series-argument buffers into deterministic class members covered by checkpoints
• isolate nested helpers, switch-arm state, and UDT methods per call site
• preserve push/update history behavior across same-bar recalculations

Why

Historical fill recalculation must be transactional: failed candidate paths cannot leak mutated Pine state, and each call site must retain independent history. The prior generated code had no aggregate checkpoint surface and used synthetic function-local buffers outside rollback.

Validation

• calc-on-fill + determinism: 12/12
• compile smoke: 37/37
• full pytest: 1466 passed / 1 skipped
• linked engine integrations and five exact sentinels passed
• full immutable-TV sweep: 412 strategies, stable error inventory, 2 tier upgrades / 0 regressions
• protected TV, metrics, inputs, verifier, and tier key sets unchanged

Companion: pineforge-engine#87 supplies the fill scheduler and checkpoint lifecycle.