Finalize MA bucket closes and extend MA rendering test

[qqrm]

Summary

• track open aggregate buckets to call update_on_close before rollover and persist state across updates F:src/domain/chart/entities.rs#L16-L244
• expand historical MA rendering test to cover multi-minute buckets, EMA data, and geometry continuity F:tests/historical_ma_render.rs#L1-L129

Testing

• cargo fmt --all
• cargo check --tests --benches
• cargo clippy --tests --benches --fix --allow-dirty -- -D warnings
• cargo test (fails: wasm binary cannot execute in host runner)

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https://chatgpt.com/codex/tasks/task_e_68cb93576aac8332a34d7f0f524ef072