Add Strategy29 cross-timeframe summary

[jackhai9]

Summary

• add an opt-in read-only Strategy29 cross-timeframe gateway summary panel
• isolate gateway failures and credentials from the local chart observer and page realm
• make chart mutation ownership safe across page and userscript realms
• publish Strategy29 userscript 0.2.0 with strict gateway contracts and bounded polling

Validation

• npm run test:binance-strategy29-bollinger (113 passed)
• npm test (808 passed)
• npm run check:binance-userscripts
• npm run inspect:binance-strategy29-bollinger
• npm run test:ui (64 passed)
• generated artifact coexistence in both load orders (2 passed)
• deterministic generated artifact SHA-256: 5c322221b377a73c171b988a72b9f41bc0ffb9d8796eac6fb5b74febfa9acb5a