feat(sing-box): add resilient AI proxy routing

[LIghtJUNction]

Summary

• add a dedicated non-China/Hong Kong ai-proxy selector for ChatGPT, Gemini, Grok, and Claude
• persist selector choices and safely replay valid selections after restart or subscription activation
• make subscription refresh direct-by-default, bounded, locked, and transactional
• restart only the verified MagicNet sing-box process and restore the previous config on activation failure
• prepare v1.1.20 release metadata

Testing

• cargo fmt --check
• cargo check --workspace
• cargo test --workspace (54 passed)
• subscription policy, AI routing, fake-Magisk smoke
• WebUI typecheck/build, kam validate, JSON and diff checks
• PHK110 subscription activation, selector persistence, four AI HTTP probes, routing chain, and browser ChatGPT load

Notes

• X media endpoints responded, but in-app playback and an unplugged-device restart cycle were not completed before disconnect.
• Local kam build was blocked before packaging by transient GitHub dependency TLS/tag API failures. CI must build and validate v1.1.20 before release.
• Base config landed in feat(routing): add dedicated AI proxy selector MagicSingBox#4.

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