Add trailing stop orders activation_price support for Rust

[nicolad]

#	Concern / Feature	Cython status (prod.)	Rust status after PR	Rust unit-tests present?
1	activation_price field on TrailingStopMarketOrder	✅ (#2610)	✅ (struct field, getter, has_activation_price)	✅ (trailing_stop_market init tests)
2	activation_price field on TrailingStopLimitOrder	✅	✅	✅ (trailing_stop_limit init tests)
3	is_activated + set_activated() logic on both trailing types	✅	✅ (new flag & method)	✅ (activation path covered)
4	Order-trait accessor activation_price()	n/a (Python only)	✅ (trait extended)	🟡 (trait exercised via concrete orders)
5	StopOrderAny::stop_px() returns activation_price fallback	n/a	✅ (method patched)	✅ (stop_px parity check)
6	Matching-core skips stop-trigger until order activated	✅	✅ (match_stop_order guard)	✅ (core unit-tests)
7	Matching-engine auto-sets activation px from market if None	✅	✅ (maybe_activate_trailing_stop)	✅
8	trailing_stop_calculate() signature now accepts activation price	✅	✅ (extra param)	✅ (calc tests)
9	Order-emulator mirrors engine logic for activation & trailing move	✅	✅ (updated method)	🟡 (covered indirectly)
10	Display / Debug output includes activation_price	✅ (str/repr tests)	✅ (fmt changes)	✅ (string/repr tests)

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#2635

[cjdsellers]

Thanks for all of this work @nicolad!