feat(perps): report margin-mode support and Lighter margin-mode lock

[abretonc7s]

Explanation

Follow-up to #10414 (stacked on it; retarget to main once it merges).

• supportedMarginModes in order capabilities. Clients decided Cross availability themselves (provider is HyperLiquid, market is not HIP-3, asset is not onlyIsolated/marginMode-restricted). That is venue logic leaking into clients. Ready order capabilities now carry an optional supportedMarginModes. HyperLiquid reports ['isolated', 'cross'] for main-DEX markets and ['isolated'] for HIP-3 or isolated-only assets, computed by a single #isCrossMarginSupported predicate that #validateMarginMode also uses, so the advertised modes and placement validation cannot drift. The field is optional: omitted means the provider does not report it and clients should not offer an explicit mode.
• LighterProvider.getMarginModeLock. Lighter also binds the margin mode per market (UpdateLeverage carries the wire mode). The existing position-row read was extracted into #readPositionMarginMode (the leverage-update path keeps its current fallback behavior); the new method reports locked with the open position's mode (a missing field means cross), unlocked when flat, or unavailable on read failure. Only open positions lock the mode here; resting orders are not treated as a lock.

References

• Follow-up to feat(perps): expose margin-mode lock and supported margin modes per market #10414
• Consumer: MetaMask Mobile Perps Pro cross margin (TAT-3524)

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