refactor: dedupe sentry trace

[gambinish]

Explanation

Gaps to close (likely in the sibling client PRs, not core)

• late_success/late_error is the taxonomy used, rather than timeout so some dashboards may need to be updated.
• docs/perps/perps-sentry-reference.md (mobile) still needs updating to describe the new controller-owned trace semantics and the removal of the toast trace.
• removing usePerpsMeasurement({ traceName: PerpsOrderSubmissionToast }) from usePerpsOrderExecution.ts, deleting the PerpsOrderSubmissionToast TraceName from app/util/trace.ts, and the mobile-side Promise.race.
• the core tests cover the meaningful equivalents (fast/late success, fast/late error). The literal "timeout" and "navigation-away" cases don't apply in core; that's fine, but the epic's mobile PR should still cover navigation-away at the UI layer if any UI tracing remains.

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Medium Risk
Touches the order submission hot path and changes trace taxonomy (late_success/late_error vs prior UI timeout traces), but does not cancel in-flight orders or alter provider execution semantics.

Overview
Centralizes Perps Place Order Sentry tracing in TradingService.placeOrder and drops the unused Perps Order Submission Toast trace name from PerpsTraceName.

Adds PlaceOrderTimeoutMs (60s) as an observational threshold only: when the provider round-trip exceeds it, the service emits a warning breadcrumb and still awaits provider.placeOrder to completion (no Promise.race / client-side cancel). Trace end data can include reason: late_success, late_error, or error (including in the catch path after the threshold). Timers are cleared in success and finally.

New unit tests cover fast vs late success/error and timer cleanup. Changelog documents the behavior and the late_error catch fix.

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