feat(x8): add native support and prepare v1.16.0 RC

[vntrevx]

Adds capability-checked Native X8 support and prepares v1.16.0-rc.1. The source compiler handles the qualified X8 entry, exit, stake/leverage, order-state and adjustment settings. Unknown exact semantics continue to fail closed, and archived X7 contracts and certificates keep their original identities.

Captured evidence covers the implemented branches and settings. The previous 54-case qualification matched 136 trades, 743 orders and 103,968 portfolio states. Two additional unchanged-source, three-day ETH Spot/Futures captures match four natural trades, eight orders, 1,728 portfolio states and 147 callback snapshots. Transformed branch probes and the limited natural-signal scope are disclosed in docs/x8-support.md; this is not complete-configuration or long-run certification.

The release adds installed-wheel X8 Spot/Futures gates on Linux x86_64/aarch64, macOS arm64 and Windows WSL2 while retaining X7 platform and clean-room checks. Normal host sizing remains automatic; explicit CPU/memory caps survive profile recalibration and propagate to official comparison. Large captured blobs are compressed without changing their original manifests or hashes and are restored with checksum verification before full CI tests.

Validation:

• Prior complete Linux suites: 2,535 Python tests passed (55 skipped), 458 Rust tests passed (2 ignored); historical source scope is recorded in the qualification.
• Resource changes: 123 focused tests passed; release-related checks: 27 passed; blob restoration: 3 passed.
• Ruff, Basedpyright, Rustfmt, locked dependency checks and CI-policy checks passed locally.
• Final candidate CI and installed-wheel results are required before release publication.

Behavior risks include newly compiled opening-candle source exits, stake/capacity bounds, fee accounting and stateful adjustments. Zero-tolerance captured trade/full-state comparisons cover these changes. Position stacking, cross-margin multi-currency collateral, arbitrary future strategy revisions and universal X8 settings support are not claimed. Stable promotion is outside this RC step.

Final branch CI passed on ee90c718417c2c5785ea18c49875ef64cd717bc4: run 34196982654. Linux Python: 2,593 passed / 32 skipped. macOS Python: 2,361 passed / 264 skipped. Rust: 458 passed / 2 ignored. Required CI also passed the AST identity lanes, quality checks, and Native full-parity fixtures. The PR-triggered Required CI remains the protected merge gate.

[chatgpt-codex-connector]

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